Prechamber Ignition System

ABSTRACT

Generally, embodiments of a pre-chamber unit having a pre-combustion chamber including one or more induction ports in a configuration which achieves flow fields and flow field forces inside the pre-combustion chamber which act to direct flame growth away quenching surface of the pre-combustion chamber.

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/925,908 entitled “Prechamber Ignition System,” and filedOct. 28, 2015; which is a continuation of U.S. patent application Ser.No. 13/997,680 entitled “Prechamber Ignition System,” and filed Dec. 24,2013 and published as United States Patent Application Number2014-0102404 A1; which is the national stage for International PatentCooperation Treaty Application PCT/2011/002012, filed Dec. 30, 2011,which claims the benefit of U.S. Provisional Patent Application No.61/460,337, filed Dec. 31, 2010, entitled “High efficiency ricocheteffect passive chamber spark plug”. The entirety of each of theforegoing patent applications and patent application publications isincorporated by reference herein.

I. TECHNICAL FIELD

Generally, embodiments of a pre-chamber unit having a pre-combustionchamber including one or more induction ports in a configuration whichachieves flow fields and flow field forces inside the pre-combustionchamber which direct flame growth away from quenching surfaces of thepre-combustion chamber.

Specifically, embodiments of a pre-combustion chamber having an internalsurface and one or more induction ports in a configuration which directsthe fuel-oxidizer mixture of in-filling streams to ricochet from one ormore locations on the internal surface of the pre-combustion chamber toachieve a flow field and flow field forces inside of the pre-combustionchamber which direct flame growth away from flame quenching surfaces ofthe pre-combustion chamber.

II. BACKGROUND

Engines operating on gaseous fuels, such as natural gas, may be suppliedwith a lean fuel mixture having a relatively high ratio of oxidizer tofuel. Conventional pre-chamber spark plugs may be used to enhance thelean flammability limits in lean burn engines. As one example, U.S. Pat.No. 7,922,551 describes a pre-chamber spark plug which reduces electrodeerosion by spreading the discharge energy over a wider surface area viaa swirling effect created by periphery holes in an end cap. However, ingeneral there remain a number of unresolved disadvantages with the useof conventional pre-chamber spark plugs in lean burn engines andspecifically as described in U.S. Pat. No. 7,922,551, as follow.

A first substantial disadvantage with conventional pre-chamber sparkplugs may be that the configuration of the pre-combustion chamber doesnot adequately concentrate fuel at the spark gap region of the sparkplug. One aspect of this disadvantage can be that the flow field forceswithin the spark gap region may be disorganized or even result in deadzones in which there is very little or no flow field. This can result inflame kernel quenching as there are no flow field forces to move theflame kernel away from the quenching surfaces.

A second substantial disadvantage with conventional pre-chamber sparkplugs may be that the configuration of the pre-chamber promotes flamekernel development in proximity to flame quenching surfaces or promotesflame growth toward flame quenching surfaces.

A third substantial disadvantage with conventional pre-chamber sparkplugs may be that the configuration of the pre-chamber may not mixin-filling streams with residual gases to sufficiently lower thetemperature inside of the pre-chamber or the internal surface of thepre-chamber which may result in auto-ignition of the fuel-oxidizermixture.

A fourth substantial disadvantage with conventional pre-chamber sparkplugs may be that the configuration of the pre-chamber may not result insufficiently fast burn rates with lean fuel mixtures resulting indeployment of flame jets into the main combustion chamber which bycomparison with faster burn rates have lesser momentum.

These and other unresolved disadvantages with conventional pre-chamberspark plugs which can result in one or more slow and unstable combustionof fuel-oxidizer mixtures, flame quenching, auto-ignition, and decreasedmomentum of flame jets are addressed by the instant invention.

III. DISCLOSURE OF INVENTION

Accordingly, a broad object of the invention can be to provideembodiments of the pre-combustion chamber of pre-combustion chamberunits having configurations which generate flow fields and flow fieldforces inside the pre-combustion chamber which can achieve in comparisonto conventional pre-chamber spark plugs one or more of: increasedfuel-oxidizer mixture ratio in the electrode gap region, a flow fieldwithin the electrode gap which reduces flow of fuel-oxidizer mixturestoward flame quenching surfaces or creates a flow of fuel-oxidizermixture directed or moving away from flame quenching surfaces, increasesfuel-oxidizer mixture ratio in the central region of the pre-combustionchamber, directs or moves flame growth away from flame quenchingsurfaces, directs or moves flame growth toward the central region of thepre-combustion chamber, directs or moves flame growth toward the regionof the pre-combustion chamber having increased fuel-oxidizer mixtureratio, increases mixing of in-filling streams with the residualcombustion gases, increases burn rates of fuel-oxidizer mixtures, andgenerates increased momentum of flame jets.

Another broad object of the invention can be to provide embodiments ofthe pre-combustion chamber of pre-combustion chamber units havingconfigurations which generate flow fields and flow field forces insidethe pre-combustion chamber which can achieve one or more of: a firstrecirculation zone associated with the electrode gap having sufficientflow field forces upon ignition of the fuel-oxidizer mixture inside thepre-combustion chamber to move the flame kernel away from flamequenching surfaces of the pre-combustion chamber or reduces movement ofthe flame kernel toward quenching surfaces of the pre-combustionchamber, a second recirculation zone having an increased fuel-oxidizermixture ratio (increased mass of fuel per unit volume or increased fuelconcentration) approaching the center of the pre-combustion chamber, anda third recirculation zone having increased mixing of residual gaseswith in-filling streams.

Another broad object of the invention can be to provide embodiments of apre-chamber spark plug which include a pre-combustion chamber havingconfigurations which generate the inventive flow fields and inventiveflow field forces inside the pre-combustion chamber which can achieveone or more of: a first recirculation zone associated with the electrodegap having sufficient flow field forces upon ignition of thefuel-oxidizer mixture inside the pre-combustion chamber to move theflame kernel away from flame quenching surfaces of the pre-combustionchamber or reduces movement of the flame kernel toward quenchingsurfaces of the pre-combustion chamber, a second recirculation zonehaving an increased fuel-oxidizer mixture ratio (increased mass of fuelper unit volume or increased fuel concentration) approaching the centerof the pre-combustion chamber, and a third recirculation zone havingincreased mixing of residual gases with in-filling streams.

Another broad object of the invention can be to provide a method ofmaking or using pre-combustion chamber units which achieves one or moreof the above-described inventive recirculation zones, flow fields, orflow field forces among a plurality of different configurations ofpre-combustion chamber units to provide one or more of the advantagesof: increased fuel-oxidizer mixture ratio in the electrode gap region, aflow field within the electrode gap which reduces flow of fuel-oxidizermixtures toward flame quenching surfaces or creates a flow offuel-oxidizer mixture directed or moving away from flame quenchingsurfaces, increases the fuel-oxidizer mixture ratio in the centralregion of the pre-combustion chamber, directs or moves flame growth awayfrom flame quenching surfaces, directs or moves flame growth toward thecentral region of the pre-combustion chamber, directs or moves flamegrowth toward the region of the pre-combustion chamber having increasedfuel-oxidizer mixture ratio, increases mixing of in-filling streams withthe residual combustion gases, increases burn rates of fuel-oxidizermixtures inside the pre-combustion chamber, and generates increasedmomentum of flame jets deployed to the main combustion chamber of anengine.

Naturally, further objects of the invention are disclosed throughoutother areas of the specification, drawings, and claims.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a reciprocating engine including a particularembodiment of the inventive pre-chamber unit.

FIG. 2 is an enlarged cross-section view 2-2 as shown in FIG. 1 whichshows a particular embodiment of the inventive flow field inside thepre-combustion chamber of a pre-chamber unit.

FIG. 3 is an enlarged cross-section view 2-2 as shown in FIG. 1 whichshows a conventional flow field inside the pre-combustion chamber ofconventional pre-chamber spark plug.

FIG. 4 is an enlarged cross-section view 2-2 as shown in FIG. 1 whichshows a particular embodiment of the inventive flow field inside thepre-combustion chamber of a pre-chamber unit.

FIG. 5 is an enlarged cross-section view 2-2 as shown in FIG. 1 whichshows a second particular embodiment of the inventive flow field insidethe pre-combustion chamber of a pre-chamber unit.

FIG. 6 is an enlarged cross-section view 2-2 as shown in FIG. 1 whichshows conventional flame growth and flame jets resulting from combustionof a fuel-oxidizer mixture having a conventional flow field inside thepre-combustion chamber of conventional pre-chamber spark plug.

FIG. 7 is an enlarged cross-section view 2-2 as shown in FIG. 1 whichshows inventive flame growth and flame jets resulting from combustion ofa fuel-oxidizer mixture having an inventive flow field inside thepre-combustion chamber of a pre-chamber unit.

FIG. 8 is a side view of a first electrode and a second electrode in theform of a J-gap.

FIG. 9 is an enlarged cross-section top view of the first electrodeshown in FIG. 8 which shows a conventional flow field and conventionalflow field forces in the electrode gap of the J-gap.

FIG. 10 is an enlarged cross-section top view of the first electrodeshown in FIG. 8 which shows an inventive flow field and inventive flowfield forces in the electrode gap of the J-gap.

FIG. 11 is an enlarged cross-section view 2-2 as shown in FIG. 1 whichshows a particular embodiment of the inventive flow field inside thepre-combustion chamber of a pre-chamber unit which creates the inventiveflow field and inventive flow field forces in the electrode gap of theJ-gap shown in FIG. 10.

FIG. 12 is an enlarged side view of a first electrode and a secondelectrode in the form of a J-gap structure which illustratesconventional initial flame growth resulting from conventional flowfields having conventional flow field forces in the electrode gapsimilar to FIG. 9.

FIG. 13 is an enlarged side view of a first electrode and a secondelectrode in the form of a J-gap structure which illustratesconventional flame growth subsequent to the initial flame growth shownin FIG. 12 resulting from conventional flow fields having conventionalflow field forces in the electrode gap.

FIG. 14 is an enlarged side view of a first electrode and a secondelectrode in the form of a J-gap structure which illustratesconventional flame growth subsequent to the flame growth shown in FIG.13 resulting from conventional flow fields having conventional flowfield forces in the electrode gap.

FIG. 15 is an enlarged side view of a first electrode and a secondelectrode in the form of a J-gap structure which illustrates inventiveinitial flame growth resulting from the inventive flow fields havinginventive flow field forces in the electrode gap as shown in FIGS. 10and 11.

FIG. 16 is an enlarged side view of a first electrode and a secondelectrode in the form of a J-gap structure which illustrates inventiveflame growth subsequent to the initial flame growth shown in FIG. 15showing movement of the flame kernel within the electrode gap resultingfrom the inventive flow fields having inventive flow field forces in theelectrode gap as shown in FIGS. 10 and 11.

FIG. 17 is an enlarged side view of a first electrode and a secondelectrode in the form of a J-gap structure which illustrates inventiveflame growth subsequent to the flame growth shown in FIG. 16 showingmovement of the flame kernel within the electrode gap resulting from theinventive flow fields having inventive flow field forces in theelectrode gap as shown in FIGS. 10 and 11.

FIG. 18 is an enlarged end view which shows a first electrode in theform of a central electrode and a second electrode in the form of a dualbar structure.

FIG. 19 is an enlarged end view which shows a first electrode in theform of a central electrode and a second electrode in the form of aJ-gap.

FIG. 20 is an enlarged end view which shows a first electrode in theform of a central electrode and a second electrode in the form of anannular ring.

FIG. 21 is an enlarged end view which shows a first electrode in theform of a massive central electrode and a second electrode in the formof a four prong structure.

FIG. 22 is an enlarged end view which shows a first electrode in theform of a central electrode and a second electrode in the form of athree prong structure.

FIG. 23 is an enlarged end view which shows a first electrode in theform of a massive square central electrode and a second electrode in theform of a four prong structure.

FIG. 24 is an enlarged end view which shows a first electrode in theform of a square central electrode and a second electrode in the form ofa four bar structure.

FIG. 25 is an enlarged cross-section view 25-25 as shown in FIG. 28 of aparticular embodiment of an inventive pre-combustion chamber of apre-combustion chamber structure which encloses a pre-combustion chambervolume including a first pre-combustion chamber volume and a secondpre-combustion chamber volume with a first electrode in the form of acentral electrode and a second electrode in the form of a dual bar asshown in FIG. 18.

FIG. 26 is an enlarged cross-section view 25-25 as shown in FIG. 28 of aparticular embodiment of an inventive pre-combustion chamber structurewhich illustrates the first pre-chamber volume.

FIG. 27 is an enlarged cross-section view 25-25 as shown in FIG. 28 of aparticular embodiment of an inventive pre-combustion chamber of apre-combustion chamber structure which illustrates the secondpre-chamber volume.

FIG. 28 is a perspective view of a particular embodiment of an inventivea pre-combustion chamber structure which illustrates certain dimensionalrelationships.

FIG. 29 is an enlarged cross-section view 25-25 as shown in FIG. 28which illustrates certain dimensional relationships of a particularembodiment of an inventive pre-combustion chamber structure.

FIG. 30 is an enlarged cross-section view 30-30 as shown in FIG. 33 of aparticular embodiment of an inventive pre-combustion chamber of apre-combustion chamber structure which encloses a pre-combustion chambervolume including a first pre-combustion chamber volume and a secondpre-combustion chamber volume with a first electrode in the form of acentral electrode and a second electrode in the form of a J-gap as shownin FIG. 19.

FIG. 31 is an enlarged cross-section view 30-30 as shown in FIG. 33 of aparticular embodiment of an inventive pre-combustion chamber structurewhich illustrates the first pre-chamber volume.

FIG. 32 is an enlarged cross-section view 30-30 as shown in FIG. 33 of aparticular embodiment of an inventive pre-combustion chamber of apre-combustion chamber structure which illustrates the secondpre-chamber volume.

FIG. 33 is a top view of a particular embodiment of an inventive apre-combustion chamber structure which illustrates certain dimensionalrelationships.

FIG. 34 is an enlarged cross section view 30-30 as shown in FIG. 33which illustrates the dimensional relationships of a particularembodiment of an inventive pre-combustion chamber structure.

FIG. 35 is a top view of a particular embodiment of an inventive apre-combustion chamber structure which illustrates certain dimensionalrelationships.

FIG. 36 is a side view of a particular embodiment of an inventive apre-combustion chamber structure which illustrates certain dimensionalrelationships.

FIG. 37 is a top view of a particular embodiment of an inventive apre-combustion chamber structure which illustrates certain dimensionalrelationships.

FIG. 38 is a side view of a particular embodiment of an inventive apre-combustion chamber structure which illustrates certain dimensionalrelationships.

FIG. 39 depicts uniform flow velocity and magnitude in the gap of apermanent passive prechamber with a removable spark plug in accordancewith certain embodiments.

FIG. 40 depicts uniform Lambda distribution in the gap of a permanentpassive prechamber with a removable spark plug in accordance withcertain embodiments.

FIG. 41 depicts a correlation between the type of fuel, the Low HeatingValue (LHV) and the fuel Methane Number (MN) in accordance with certainembodiments.

FIG. 42 depicts a permanent passive prechamber with removable spark plugfor natural gas fueled engines in accordance with certain embodiments.

FIG. 43 depicts a permanent passive prechamber with removable spark plugfor low BTU fueled engines in accordance with certain embodiments.

FIG. 44 depicts a permanent passive prechamber with removable spark plugfor greater than about 60 MN fueled engines in accordance with certainembodiments.

FIG. 45 depicts a permanent passive prechamber with removable spark plugfor low MN fueled engines in accordance with certain embodiments.

FIG. 46 depicts uniform flow velocity and magnitude in the gap of aforward flow prechamber spark plug in accordance with certainembodiments.

FIG. 47 depicts uniform Lambda distribution in the gap of a forward flowprechamber spark plug in accordance with certain embodiments.

FIG. 48 depicts a temperature distribution in the major elements of aforward flow prechamber spark plug in accordance with certainembodiments.

FIG. 49 depicts a temperature distribution in the major elements of aremovable spark plug and permanent prechamber in accordance with certainembodiments.

FIG. 50 depicts an active scavenge prechamber spark plug with ascavenging port located remotely from the radial gap in accordance withcertain embodiments.

FIG. 51 depicts an active scavenge prechamber spark plug with ascavenging port located adjacent to the radial gap in accordance withcertain embodiments.

FIG. 52 depicts a flow velocity pattern and uniform magnitude in asingle radial gap of an active scavenge prechamber spark plug inaccordance with certain embodiments.

FIG. 53 depicts uniform flow velocity and magnitude (1501) in a singleradial gap of an active scavenge prechamber spark plug in accordancewith certain embodiments.

FIG. 54 depicts Lambda stratification in a prechamber in accordance withcertain embodiments.

FIG. 55 depicts uniform Lambda distribution in the single radial gap inaccordance with certain embodiments.

FIG. 56 depicts a temperature distribution in the major elements of anactive scavenge prechamber spark plug with single radial gap inaccordance with certain embodiments.

FIG. 57 depicts a removable spark plug with radial gap, screwed into apre-chamber in accordance with certain embodiments.

V. MODE(S) FOR CARRYING OUT THE INVENTION

In certain embodiments, a method of distributing a fuel-oxidizer mixturein a pre-combustion chamber is described, comprising: providing apre-combustion chamber comprising at least one induction port thatcommunicates between an external surface and an internal surface of saidpre-combustion chamber; providing a spark plug comprising: a primaryelectrode; one or more ground electrodes offset radially from theprimary electrode to form one or more electrode gaps; removablyattaching the spark plug to the pre-combustion chamber so that the oneor more electrode gaps are disposed within the pre-combustion chambervolume; and directing a fuel-oxidizer mixture into the pre-combustionchamber via the at least one induction port to reduce interaction of aflame kernel with an internal surface of said pre-combustion chamber.The pre-combustion chamber may further comprise a first plurality ofthreads for removably engaging a second plurality of threads on thespark plug to removably attach the spark plug to the pre-combustionchamber. The pre-combustion chamber may be permanently affixed to anengine cylinder head. The pre-combustion chamber may be configured togenerate a flow velocity in the one or more electrode gaps of the sparkplug that is substantially uniform in magnitude and direction when afuel air mixture is ignited in the pre-combustion chamber. Thepre-combustion chamber may be configured to direct a flow from the oneor more electrode gaps of the spark plug away from quenching surfacesand toward one or more of the one or more holes when a fuel air mixtureis ignited in the pre-combustion chamber. The method may furthercomprise directing a fuel-oxidizer mixture into the pre-combustionchamber via the at least one induction port to reduce flow fieldvelocities approaching said internal surface of said pre-combustionchamber to reduce quenching of flame growth. The method may furthercomprise directing a fuel-oxidizer mixture into the pre-combustionchamber via the at least one induction port to increase saidfuel-oxidizer mixture ratio in said electrode gap. The method mayfurther comprise directing a fuel-oxidizer mixture into thepre-combustion chamber via the at least one induction port to reducevelocity of said flame kernel movement towards said internal surface ofsaid pre-combustion chamber.

In certain embodiments, a method of distributing a fuel-oxidizer mixturein a pre-combustion chamber is disclosed, comprising providing apre-combustion chamber comprising: at least one induction port whichcommunicates between an external surface and an internal surface of saidpre-combustion chamber; the at least one induction port configured toaim at least one infilling stream of said fuel-oxidizer mixture at saidinternal surface of said pre-combustion chamber; and providing a sparkplug comprising: a primary electrode; one or more ground electrodesoffset radially from the primary electrode to form one or more electrodegaps; removably attaching the spark plug to the pre-combustion chamberso that the one or more electrode gaps are disposed within thepre-combustion chamber volume; and introducing at least one infillingstream of fuel-oxidizer mixture into the pre-combustion chamber via theat least one induction port. The pre-combustion chamber may furthercomprise a first plurality of threads for removably engaging a secondplurality of threads on the spark plug to removably attach the sparkplug to the pre-combustion chamber. The pre-combustion chamber may bepermanently affixed to an engine cylinder head. The pre-combustionchamber may be configured to generate a flow velocity in the one or moreelectrode gaps of the spark plug that is substantially uniform inmagnitude and direction when a fuel air mixture is ignited in thepre-combustion chamber. The pre-combustion chamber may be configured todirect a flow from the one or more electrode gaps of the spark plug awayfrom quenching surfaces and toward one or more of the one or more holeswhen a fuel air mixture is ignited in the pre-combustion chamber. Themethod may further comprise configuring said at least one induction portto aim at least one infilling stream of said fuel-oxidizer mixture atleast one point location on said internal surface of said pre-combustionchamber selected from the group consisting of: a core nose of a centralinsulator, an upper corner of said core nose of said central insulator,one or more electrodes, and said shell. The method may further comprisericocheting said at least one infilling stream from said internalsurface of said pre-combustion chamber to achieve reduced interaction ofsaid flame kernel with said internal surface of said pre-combustionchamber.

In certain embodiments, a pre-chamber unit is disclosed, comprising: apre-combustion chamber; and at least one induction port whichcommunicates between an external surface and an internal surface of saidpre-combustion chamber, said at least one induction port configured todirect a fuel-oxidizer mixture into the pre-combustion chamber togenerate flow field forces within said pre-combustion chamber which uponignition of a fuel-oxidizer mixture reduce the interaction of a flamekernel with said internal surface of said pre-combustion chamber;wherein the pre-combustion chamber is configured for removably receivinga spark plug comprising a primary electrode and one or more groundelectrodes disposed within the pre-combustion chamber volume and offsetradially from the primary electrode to form one or more electrode gaps,such that the one or more electrode gaps are disposed within thepre-combustion chamber volume. The one or more ground electrodes maycomprise a single ground electrode offset radially from the primaryelectrode to form a single electrode gap. The pre-combustion chamber mayfurther comprise a first plurality of threads for removably engaging asecond plurality of threads on the spark plug to removably attach thespark plug to the pre-combustion chamber. The pre-combustion chamber maybe permanently affixed to an engine cylinder head. The pre-combustionchamber may be configured to generate a flow velocity in the one or moreelectrode gaps of the spark plug that is substantially uniform inmagnitude and direction when a fuel air mixture is ignited in thepre-combustion chamber. The pre-combustion chamber may be configured todirect a flow from the one or more electrode gaps of the spark plug awayfrom quenching surfaces and toward one or more of the one or more holeswhen a fuel air mixture is ignited in the pre-combustion chamber. The atleast one induction port may be configured to aim at least one infillingstream toward said internal surface of said pre-combustion chamber toreduce the interaction of said flame kernel with said internal surfaceof said pre-combustion chamber. The at least one induction port may beconfigured to aim at least one infilling stream toward a selected one ormore of: a nose of a central insulator, an upper corner of a nose of acentral insulator, a lower corner of a nose of a central insulator, aside surface of a nose of a central insulator, and a shell. The at leastone induction port may be configured to develops flow field forces whichincrease mixing of an amount of residual gases within saidpre-combustion chamber with said in-filling streams to reducetemperature of said internal surface of said pre-chamber or said amountof residual gases.

In certain embodiments, a method of distributing a fuel-oxidizer mixturein a pre-combustion chamber is disclosed, comprising: providing apre-combustion chamber comprising: a primary electrode and one or moreground electrodes disposed within the pre-combustion chamber, theprimary electrode and the ground electrode disposed a distance apart toprovide one or more electrode gaps; at least one induction port whichcommunicates between an external surface and an internal surface of saidpre-combustion chamber; and directing a fuel-oxidizer mixture into thepre-combustion chamber via the at least one induction port to reduceinteraction of a flame kernel with an internal surface of saidpre-combustion chamber. The ground electrodes may comprise a singleground electrode disposed a distance apart from the primary electrode toform a single electrode gap. The single ground electrode may have asurface area greater than about 1 mm² The pre-combustion chamber may beconfigured to generate a flow velocity in the single electrode gap ofthe spark plug that is less than about 100 m/s when a fuel air mixtureis ignited in the pre-combustion chamber. The pre-combustion chamber maybe configured to generate an average turbulent kinetic energy greaterthan 1 m²/s² when a fuel air mixture is ignited in the pre-combustionchamber. The pre-combustion chamber may be configured to generate asubstantially uniform lambda distribution in the single electrode gap ofthe spark plug when a fuel air mixture is ignited in the pre-combustionchamber. The pre-combustion chamber may be configured to generate alambda fuel air mixture richer than about 2.5 in the single electrodegap of the spark plug when a fuel air mixture is ignited in thepre-combustion chamber. The pre-combustion chamber may be configured togenerate an average lambda value richer than about 2.5 in thepre-combustion chamber when a fuel air mixture is ignited in thepre-combustion chamber. The volume of the pre-combustion chamber may bebetween about 1000 mm³ and about 6000 mm³ for use with fuels with energycontent greater than about 800 BTU/ft³. The pre-combustion chamber mayhave a total volume greater than about 1000 mm³ for use with fuels withenergy content less than about 800 BTU/ft³. The pre-combustion chambermay have a total volume less than about 6000 mm³ for use with fuels withMethane Number lower than about 60. The pre-combustion chamber may havea total volume between about 1000 mm³ and about 6000 mm³ for use withfuels with Methane Number greater than about 60. The method may furthercomprise directing a fuel-oxidizer mixture into the pre-combustionchamber via the at least one induction port to increase a fuel-oxidizermixture ratio within said pre-combustion chamber toward a center of saidpre-combustion chamber. The method may further comprise directing afuel-oxidizer mixture into the pre-combustion chamber via the at leastone induction port to reduce quenching of said flame kernel on saidinternal surface of said pre-combustion chamber. The method may furthercomprise: surrounding a first of said one or more electrodes with acentral insulator, said central insulator encased in a shell extendingoutwardly about said one or more electrodes; and generating flow fieldforces within said electrode gap sufficient to reduce interaction ofsaid flame kernel with said central insulator. The method may furthercomprise generating a flow field velocity within said electrode gap ofbetween about 1.0 meter per second and about 100.0 meters per second.

In certain embodiments, a method of distributing a fuel-oxidizer mixturein a pre-combustion chamber is disclosed, comprising providing apre-combustion chamber comprising: a primary electrode and a groundelectrode disposed within the pre-combustion chamber, the primaryelectrode and the ground electrode disposed a distance radially apart toprovide a single electrode gap; at least one induction port whichcommunicates between an external surface and an internal surface of saidpre-combustion chamber; the at least one induction port configured toaim at least one infilling stream of said fuel-oxidizer mixture at saidinternal surface of said pre-combustion chamber; and introducing atleast one infilling stream of fuel-oxidizer mixture into thepre-combustion chamber via the at least one induction port. The groundelectrode may comprise an electrode surface area greater than about 1mm². The pre-combustion chamber may be configured to generate a flowvelocity in the single electrode gap of the spark plug that is less thanabout 100 m/s when a fuel air mixture is ignited in the pre-combustionchamber. The pre-combustion chamber may be configured to generate anaverage turbulent kinetic energy greater than 1 m²/s² when a fuel airmixture is ignited in the pre-combustion chamber. The pre-combustionchamber may be configured to generate a substantially uniform lambdadistribution in the single electrode gap of the spark plug when a fuelair mixture is ignited in the pre-combustion chamber. The pre-combustionchamber may be configured to generate a lambda fuel air mixture richerthan about 2.5 in the single electrode gap of the spark plug when a fuelair mixture is ignited in the pre-combustion chamber. The pre-combustionchamber may be configured to generate a lambda fuel air mixture richerthan in a second region between the single electrode gap of the sparkplug and a bottom surface of the pre-combustion chamber when a fuel airmixture is ignited in the pre-combustion chamber. The pre-combustionchamber may be configured to generate an average lambda value richerthan about 2.5 in the pre-combustion chamber when a fuel air mixture isignited in the pre-combustion chamber. The volume of the pre-combustionchamber may be between about 1000 mm³ and about 6000 mm³ for use withfuels with energy content greater than about 800 BTU/ft³. Thepre-combustion chamber may have a total volume greater than about 1000mm³ for use with fuels with energy content less than about 800 BTU/ft³.The pre-combustion chamber may have a total volume less than about 6000mm³ for use with fuels with Methane Number lower than about 60. Thepre-combustion chamber may have a total volume between about 1000 mm³and about 6000 mm³ for use with fuels with Methane Number greater thanabout 60. The method may further comprise configuring said at least oneinduction port to aim at least one infilling stream of saidfuel-oxidizer mixture at least one point location on said internalsurface of said pre-combustion chamber selected from the groupconsisting of: a core nose of a central insulator, an upper corner ofsaid core nose of said central insulator, one or more electrodes, andsaid shell. The method may further comprise ricocheting said at leastone infilling stream from said internal surface of said pre-combustionchamber to achieve reduced interaction of said flame kernel with saidinternal surface of said pre-combustion chamber.

In certain embodiments, a pre-chamber unit is disclosed, comprising: aprimary electrode and a ground electrode disposed a distance radiallyapart to provide a single electrode gap; a pre-combustion chamber whichat least partially encloses said first electrode and said secondelectrode; and at least one induction port which communicates between anexternal surface and an internal surface of said pre-combustion chamber,said at least one induction port configured to direct a fuel-oxidizermixture into the pre-combustion chamber to generate flow field forceswithin said pre-combustion chamber which upon ignition of afuel-oxidizer mixture reduce the interaction of a flame kernel with saidinternal surface of said pre-combustion chamber. The ground electrodemay comprise an electrode surface area greater than about 1 mm². Thepre-combustion chamber may be configured to generate a flow velocity inthe single electrode gap of the spark plug that is less than about 100m/s when a fuel air mixture is ignited in the pre-combustion chamber.The pre-combustion chamber may be configured to generate an averageturbulent kinetic energy greater than 1 m²/s² when a fuel air mixture isignited in the pre-combustion chamber. The pre-combustion chamber may beconfigured to generate a substantially uniform lambda distribution inthe single electrode gap of the spark plug when a fuel air mixture isignited in the pre-combustion chamber. The pre-combustion chamber may beconfigured to generate a lambda fuel air mixture richer than about 2.5in the single electrode gap of the spark plug when a fuel air mixture isignited in the pre-combustion chamber. The pre-combustion chamber may beconfigured to generate a lambda fuel air mixture richer than in a secondregion between the single electrode gap of the spark plug and a bottomsurface of the pre-combustion chamber when a fuel air mixture is ignitedin the pre-combustion chamber. The pre-combustion chamber may beconfigured to generate an average lambda value richer than about 2.5 inthe pre-combustion chamber when a fuel air mixture is ignited in thepre-combustion chamber. The volume of the pre-combustion chamber may bebetween about 1000 mm³ and about 6000 mm³ for use with fuels with energycontent greater than about 800 BTU/ft³. The pre-combustion chamber mayhave a total volume greater than about 1000 mm³ for use with fuels withenergy content less than about 800 BTU/ft³. The pre-combustion chambermay have a total volume less than about 6000 mm³ for use with fuels withMethane Number lower than about 60. The pre-combustion chamber may havea total volume between about 1000 mm³ and about 6000 mm³ for use withfuels with Methane Number greater than about 60. The flow field velocitywithin said electrode gap may have a range of between about 1.0 m/s andabout 100.0 m/s. The at least one induction port may be configured toaim at least one infilling stream toward a selected one or more of: anose of a central insulator, an upper corner of a nose of a centralinsulator, a lower corner of a nose of a central insulator, a sidesurface of a nose of a central insulator, and a shell. The internalsurface may comprise a central insulator from which said at least oneinfilling stream is configured to ricochet to generate said flow fieldforces to increase said fuel-oxidizer mixture ratio in said electrodegap. The pre-combustion chamber may enclose a total volume of betweenabout 800 millimeters³ and about 1000 millimeters³. The at least oneinduction port may be configured to develop flow field forces whichincrease mixing of an amount of residual gases within saidpre-combustion chamber with said in-filling streams to reducetemperature of said internal surface of said pre-chamber or said amountof residual gases.

Now referring primarily to FIG. 1, a schematic diagram is shown of areciprocating piston engine (1) including a particular embodiment of theinventive pre-chamber unit (2). The reciprocating piston engine (1) maycontain one or more main combustion chambers (3). The engine (1) canhave at least one cylinder head (4) and can have one or more valves (5)which can operate to interruptedly allow flow toward or away from eachmain combustion chamber (3). A fuel-oxidizer mixture intake system (6)provides a supply passage (7) which fluidicly communicates with each ofthe main combustion chambers (3). A fuel-oxidizer mixture transfer means(8), such as a carburetor, delivers an amount of the fuel-oxidizermixture (9) through the supply passage (7) to the main combustionchambers (3). The fuel-oxidizer mixture (9) can include an amount offuel (10) (as examples, natural gas, bio-gas, gasoline, diesel, alcohol,or other fuel, or various combinations thereof), and an amount ofoxidizer (11) (such as air, oxygen, nitrous oxide, or other oxidizer, orvarious combinations thereof).

Delivery of the amount of fuel-oxidizer mixture (9) can be timed inrelation to the position of those parts of the engine (1) (such aspistons (12)) coupled to a crankshaft (not shown) which translate theexpansion of gases resulting from combustion of the amount offuel-oxidizer mixture (9) in the corresponding one of the maincombustion chambers (3) into rotational motion of the crankshaft of thereciprocating piston engine (1).

Again referring to FIG. 1, embodiments of the inventive pre-chamber unit(2) can be disposed in relation to the one or more main combustionchambers (3) of the engine (1) such that combustion of fuel-oxidizermixture (9) within the main combustion chamber (3) of the engine (1) canbe initiated in a pre-combustion chamber (13) of the pre-chamber unit(2). The fuel-oxidizer mixture (9) can have a flow field (14) within thepre-combustion chamber (13)(as shown in the examples of FIGS. 2, 4, 5)sufficiently controlled as to pressure, temperature, and distribution todeploy upon ignition one or more flame jets (15) (as shown in theexamples of FIGS. 6, 7) into the main combustion chamber (3) to combustthe amount of fuel-oxidizer mixture (9) within the main combustionchamber (3). Certain embodiments of the inventive pre-chamber unit (2)can be produced by integration or retro-fitting of the inventivepre-combustion chamber (13) and methods of controlling the flow field(14) and flow field forces (16) (as shown in the examples of FIGS. 2, 4,5, 10) within the inventive pre-combustion chamber (13) into a numerousand wide variety of conventional mass produced or serial productionindustrial spark plugs for use with reciprocating piston engines (1);however, the invention is not so limited, and embodiments of theinventive pre-chamber unit (2), inventive pre-combustion chamber (13),and methods which generate inventive flow fields (14) and inventive flowfield forces (16) within the inventive pre-combustion chamber (13) canbe utilized with a numerous and wide variety of reciprocating pistonengines (1) whether configured as 2-stroke engines, 4-stroke engines, orthe like, and can be utilized with other types of engines such as rotaryengines, Wankel engines, or the like (individually and collectively the“engine”).

Now referring primarily to FIGS. 1 and 2, particular embodiments of theinventive pre-chamber unit (2) can include a central insulator (17)which surrounds a central electrode (18). The central electrode (18)(also referred to as the “first electrode”) can be connected by aninsulated wire (19) to an ignition system (20) (such as an ignition coilor magneto circuit) on the outside the engine (1), forming, with agrounded electrode (21) (also referred to as the “second electrode”) anelectrode gap (22) (one or more electrodes can be provided in a numerousand wide variety of structural configurations depending upon theapplication, as further described below). A shell (23), typically formedor fabricated from a metal, can surround or encase a portion of thecentral insulator (17). The shell (23) provides a shell external surface(24) configured to sealably mate with the cylinder head (4) of theengine (1), typically by mated spiral threads (25) which draw thesealing surfaces together (as shown in the example of FIG. 1) to disposethe pre-combustion chamber (13) of the pre-chamber unit (2) in properrelation to the main combustion chamber (3) for ignition of thefuel-oxidizer mixture (9) therein.

Now referring primarily to FIG. 2, embodiments of the inventivepre-chamber unit (2) provide a pre-combustion chamber (13). Thepre-combustion chamber (13) can be formed by the shell (23) extendingoutwardly to at least partially enclose the central electrode (18) andthe grounded electrode (21) (as shown in the examples of FIGS. 25-27 and29). As to particular embodiments, the pre-combustion chamber (13) canbe formed by coupling a pre-combustion chamber element (26) to the baseof the shell (23) (as shown in the examples of FIGS. 2-7, 30-32 and 34).The various embodiments of the pre-combustion chamber (13) can have apre-combustion chamber wall (27) having pre-chamber external surface(28) disposed toward the internal volume of the main combustion chamber(3). The pre-combustion chamber internal surface (30) includes thecorresponding internal surface of the shell (23), the pre-combustionchamber element (26), the central insulator (17), or other internalsurfaces which enclose a pre-combustion chamber volume (29)(individually and collectively referred to as the “internal surface”(30)).

The internal surface (30) of the pre-combustion chamber (13) whetherformed by extension of the shell (23) or by coupling of a pre-combustionchamber element (26) to the base of the shell (23), or otherwise, canfurther provide one or more induction-ejection ports (31)(also referredto as “induction ports”) which communicate between the pre-combustionchamber external surface (28) and the pre-combustion chamber internalsurface (30) of the pre-combustion chamber (13). The one or moreinduction ports (31) can be configured to transfer an amount of thefuel-oxidizer mixture (9) from the main combustion chamber (3) into thepre-combustion chamber (13) and to deploy flame jets (15) from thepre-combustion chamber (13) into the main combustion chamber (3).

Combustion of the amount of fuel-oxidizer mixture (9) inside of thepre-combustion chamber (13) can be initiated by generation of a sparkacross the electrode gap (22). The induction ports (31) can beconfigured to deploy flame jets (15) into the main combustion chamber(3) at a location which results in combustion of the amount offuel-oxidizer mixture (9) within the main combustion chamber (3).

Again referring primarily to FIG. 2, as to certain embodiments of theinvention an axial induction port (32) can be substantially axiallyaligned with the central longitudinal axis (33) of the pre-chamber unit(2). As to certain embodiments, one or more side induction ports (34)can be disposed in radial spaced apart relation about the centrallongitudinal axis (33). Certain embodiments of the invention can provideboth an axial induction port (32) and one or more side induction ports(34) (as shown in the examples of FIGS. 2-7 and 33-38); however, theinvention is not so limited, and particular embodiments of the inventionmay only provide an axial induction port (32) or only side inductionports (34) depending on the application. Upon compression of the amountof fuel-oxidizer mixture (9) in the main combustion chamber (3), aportion of the amount of fuel-oxidizer mixture (9) can pass through theaxial induction port (32) and the side induction ports (34) as acorresponding one or more in-filling streams (35). The in-fillingstreams (35) of the fuel-oxidizer mixture (9) can create the flow field(14) having flow field forces (16) (represented in the examples of FIGS.3 through 11 by arrow heads pointing in the direction of flow and thevelocity being greater with increasing length of the arrow body whichallows comparison of conventional flow fields and inventive flow fields)inside of the pre-combustion chamber volume (29).

The flow field (14) and the flow field forces (16) can be analyzed usingcomputational fluid dynamics (“CFD”). Computers were used to perform thecalculations required to simulate the interaction of fuel-oxidizermixture (9) and flame growth (39) with the internal surface (30) of thepre-combustion chamber (13) defined by the various embodiments ofinventive pre-chamber units (2) and conventional pre-chamber sparkplugs. CONVERGE™ CFD software offered by Convergent Science, Inc. wasused in analysis of flow fields (14) and flow field forces (16) ofinventive pre-chamber units (2) and conventional pre-chamber sparkplugs. CFD can be used to calculate increasing fuel-oxidizer mixture (9)ratio inward of the internal surface (30) of the pre-combustion chamber(13)(or toward the center of the pre-combustion chamber), decreasingfuel-oxidizer mixture (9) ratio approaching the internal surface (30) ofpre-combustion chamber (13), or reducing flow field (14) velocitiesapproaching the internal surface (30) of pre-combustion chamber (13).

First, a pre-combustion chamber (13) whether conventional or includingone or more features in accordance with the invention can be analyzedusing CFD to quantify the flow field forces (16) and flow fieldvelocities approaching the internal surface (30) of pre-combustionchamber (13) and can also be used to quantify the distribution offuel-oxidizer mixture (9) ratio in relation to the internal surface (30)of the pre-combustion chamber (13). Secondly, the induction ports (31)of pre-combustion chamber (13) can be modified by altering one or moreof the diameter (72), length (71), angle (78), radius (75) from thecentral axis (33), the number of side induction ports (34), or swirloffset (77) (as shown in the examples of FIGS. 28, 29, and 35). Thislist of modifications is not intended to be inclusive of allmodifications or combinations or permutations of modifications possible,but are sufficient along with the description and figures for a personof ordinary skill to make and use a numerous and wide variety ofpre-chamber units (2) encompassed by the invention. Then, through CFD,an analysis can be performed to quantify the flow field forces (16) andflow field velocities approaching the internal surface (30) ofpre-combustion chamber (13) and also quantify the distribution offuel-oxidizer mixture (9) ratio in relation to the internal surface (30)of pre-combustion chamber (13). The analysis of the first CFD can becompared to the second CFD to determine if there is a reduction of flowfield forces (16) and velocities approaching internal surface (30) ofpre-combustion chamber (13), an increasing of fuel-oxidizer mixture (9)ratio inward of internal surface (30) of pre-combustion chamber (13), ora decreasing of fuel-oxidizer mixture (9) ratio approaching internalsurfaces (30) of pre-combustion chamber (13).

CFD can also be used to calculate increasing rate of flame growth (39),reduced rate of flame growth (39) due to interaction or engulfment withinternal surface (30) of pre-combustion chamber (13), or reducedquenching of flame growth (39) on internal surface (30) ofpre-combustion chamber (13) (as shown in the examples of FIGS. 6 and 7).First, a pre-combustion chamber (13) can be analyzed using CFD to locatethe flame kernel (44) with relation to the internal surface (30) andquantify the flame growth (39) rate within the pre-combustion chamber(13). Secondly, the induction ports (31) can be modified as previouslydescribed. Then, through CFD, an analysis can be performed to locate theflame kernel (44) in relation to the internal surface (30) and quantifythe flame growth (39) rate within the pre-combustion chamber (13). Theanalysis of the first CFD can be compared to the second CFD to determineincreasing flame growth (39) rate, reduced interaction or engulfment ofthe flame kernel (44) with the internal surface (30) of thepre-combustion chamber (13), or reduced quenching of the flame kernel(44) on the internal surface (30) of the pre-combustion chamber (13).

A specially configured instrumented optical engine, combined with highspeed Schlieren and Planar Laser Induced Fluorescence photography can beused to experimentally verify the CFD analytical results in terms ofincreasing flame growth (39) rate, reduced interaction of flame kernel(44) with internal surface (30) of pre-combustion chamber (13), reducedquenching of flame kernel (44) on internal surface (30) ofpre-combustion chamber (13), increasing fuel-oxidizer mixture (9) ratioinward of internal surface (30) of pre-combustion chamber (13),decreasing fuel-oxidizer mixture (9) ratio approaching internal surface(30) of pre-combustion chamber (13), or reducing flow field (14)velocities approaching internal surface (30) of pre-combustion chamber(13). Further measurements on engine combustion performance, such asHeat Released Rate (HRR) and Brake Thermal Efficiency (BTE), allow theend-effect(s) to be quantified.

Typical comparative measures between conventional pre-chamber sparkplugss and pre-chamber units (2) modified in accordance with theinvention are listed in the first column of Table 1 and include flowfield velocity meters per second (“m/s”) approaching the internalsurface (30) of the pre-combustion chamber (13), interaction betweenflame growth (39) and quenching surfaces millimeters squared (“mm²”) ofthe pre-combustion chamber (13), flame jet (15) momentum gram-meter persecond (“g-m/s”), flame growth rate m/s, and fuel-oxidizer mixtureratio. Table 1 further lists exemplary values for these measuresobtained by CFD for each of conventional pre-chamber units andpre-chamber units modified in accordance with the invention; however,the invention is not limited to these exemplary values and dependingupon the application pre-chamber units modified in accordance with theinvention in comparison to conventional pre-chamber units may yieldgreater or lesser differences in one or more of the measures.

TABLE 1 Comparison Between Conventional Pre-chamber Unit and ModifiedPre-chamber Unit Conventional Modified Pre-chamber Pre-chamberComparative Measure Unit Unit Flow Field (14) Velocity [m/s] approaching30-35 15-18 pre-combustion chamber internal surface (30) Interaction orEngulfment Between Flame 50 5 Growth (39) surface and Quenching Surfaces[mm²] Flame Jet (15) Momentum [g-m/s] 800 2800 Flame Growth (39) Rate[m/s] 7 24 Fuel-Oxidizer Mixture (9) Ratio 0.036 0.038

Now referring primarily to FIGS. 2, 4, and 5, the structure of thepre-combustion chamber external surface (28) and pre-combustion chamberinternal surface (30) of the pre-combustion chamber (13), thepre-chamber volume (29), the structure of the axial induction port (32),the structure of one or more side induction ports (34), and the overallstructural relationship of one or more of these structures (such as thedistance of the axial induction port (32) or the one or more sideinduction ports (34) from a point location (36) on the internal surface(30) which can be a pre-determined distance based on CFD analysis), asfurther described below), can be altered to correspondingly altercharacteristics of the in-filling streams (35) as to the amount of flow,the velocity of flow, the direction of flow, the interaction of thein-filling streams (35) with the internal surface (30) of thepre-combustion chamber (13) such as a point location (36))(which can bea pre-determined point location (39) based on CFD analysis), angle ofincidence (37) in relation to the point location (36)(which can be apre-determined angle of incidence (37) based on CFD analysis), at thepoint location (36), angle of rebound (38) (which can be apre-determined angle of rebound (38) based on CFD analysis) orredirection from the point location (36)(also referred to as“ricochet”), velocity of rebound from the point location (36), or thelike, as further described below. Alteration of the structures of thepre-combustion chamber (13) or the induction ports (32)(34) to altercharacteristics of the in-filling streams (35) can correspondingly altercharacteristics of the flow field (14) and associated flow field forces(16) inside of the pre-combustion chamber (13) to provide certainadvantages as compared to the characteristics of conventional flowfields and conventional flow field forces achieved in conventionalpre-chamber spark plugs.

FIGS. 2 and 4, provide illustrative examples of the results that can beobtained using methods of distributing a fuel-oxidizer mixture (9) in apre-combustion chamber (13) of a pre-chamber unit (2) and theadvantageous recirculation patterns that can be achieved in the flowfield (14) inside the pre-combustion chamber (13) by modification of thestructures of the pre-combustion chamber (13) or the induction ports(32)(34), or both, in accordance with the invention. As to particularembodiments of the invention, the structure of one or more sideinduction ports (34) in relation to the internal surface (30) of thepre-combustion chamber (13) can achieve in-filling streams (35) directedtoward the internal surface (30) of the pre-combustion chamber (13),such as a point location (36) on the shell (23), the central insulator(17), the central electrode (18), or other locations or regions ofinternal surface (30), such parameters can be adjusted to achievesimilar advantageous results between a numerous and wide variety ofdifferent firing ends (53) (or electrode configurations) enclosed by thepre-combustion chamber (13) of inventive pre-chamber units (2) (see theexamples of FIGS. 18 through 24, as further described below).

Again referring primarily to FIGS. 2, 4 and 5, as to a numerous and widevariety of embodiments of the invention, the pre-combustion chamber (13)and associated axial induction port (32) or one or more of the sideinduction ports (34) can be structured to generate characteristics inthe in-filling streams (35) to achieve a “ricochet effect”. Inaccordance with embodiments of the invention, the term “ricochet effect”means a rebound, a re-direction, an angle of deflection (38), or thelike, of one or more in-filling streams (35) from a corresponding one ormore point location(s)(36) on the internal surface (30) of thepre-combustion chamber (13) to generate a flow field (14) and associatedflow field forces (16) inside of the pre-combustion chamber volume (29)which by comparison to the conventional pre-chamber spark plugsincreases fuel-oxidizer mixture (9) ratio toward the center of thepre-combustion chamber (13) or reduces interaction of flame growth (39)with the internal surface (30) of the pre-combustion chamber (13).Increasing the fuel-oxidizer mixture (9) ratio toward the center of thepre-combustion chamber (13) or reducing the interaction of flame growth(39) or flame kernel (44) with the internal surface (30) of thepre-combustion chamber (30) can, upon ignition of the fuel-oxidizermixture (9) through a spark bridging the electrode gap (22) inside ofthe pre-combustion chamber (13), substantially increase fuel-oxidizercombustion rate and substantially increase flame growth (39) and themomentum of flame jets (15) deployed into the main combustion chambers(3) (as shown by the comparison of FIGS. 6 and 7, as further describedbelow).

The ricochet effect with respect to the in-filling streams (35) canresult in flow field forces (16) sufficient to generate a flow field(14) having one or more flow recirculation zones (40)(41)(42) orcombinations of flow recirculation zones (40)(41)(42) inside of thepre-combustion chamber (13) which may be entirely lacking, substantiallylacking, or can be enhanced in comparison to the conventional flowfields of conventional pre-chamber spark plugs, which may otherwise bestructurally or substantially identical.

Again referring primarily to FIG. 2, achieving the ricochet effect ofthe in-filling streams (35) can result in one or more of a firstrecirculation zone (40), a second recirculation zone (41), and a thirdrecirculation zone (42) of the flow field (14) inside the pre-combustionchamber (13). Each of the recirculation zones (40)(41)(42) achieved canprovide certain advantages over conventional flow fields.

The first recirculation zone (40) can achieve a counter flow region (43)in the flow field (14) associated with the electrode gap (22) havingsufficient flow field forces (16) upon ignition of the fuel-oxidizermixture (9) inside the pre-combustion chamber (13) to move the flamekernel (44) away from the internal surface (30) of the pre-combustionchamber (13), or reduce movement or velocity toward the internal surface(30), or flame quenching surfaces, of the pre-combustion chamber (13)(as shown in the example of FIG. 7) to reduce quenching of flame growth(39) caused by interaction with the internal surface (30) of thepre-combustion chamber (13) as compared to conventional flow fields. Asto particular embodiments, the flow field forces (16) in the counterflow region (43) can be sufficient to move the spark kernel (44) awayfrom quenching surfaces and into the second recirculation zone (41) (asshown in the example of FIG. 7).

The second recirculation zone (41) can achieve, by comparison withconventional flow fields, an increased fuel-oxidizer mixture (9) ratio(increased mass of fuel per volume or increased fuel concentration)approaching or toward the center of the pre-combustion chamber (13) (ora decreased mass of fuel per volume approaching the internal surface(30) of pre-combustion chamber (13)) which can result in increasedcombustion rates of the fuel-oxidizer mixture (9) inside thepre-combustion chamber (13) resulting in increased rate of flame growth(39) and increased momentum of flame jets (15) deployed to the maincombustion chamber (3) of the engine (1), as compared to conventionalflow fields (45) (as shown in the example of FIG. 7).

The third recirculation zone (42) achieves, by comparison withconventional flow fields, increased mixing of residual gases within-filling streams (35) to correspondingly reduce surface temperaturesand residual gas temperatures within the pre-combustion chamber (13),thereby reducing the tendency for auto-ignition of the fuel-oxidizermixture (9) inside the pre-combustion chamber (13).

Now referring primarily to FIGS. 3 through 5, which provide side by sidecomparisons of pre-combustion chambers (13) having substantially thesame structure in cross section. FIG. 3 shows a conventional flow field(45) which has not achieved the ricochet effect. FIGS. 4 and 5 showembodiments of the inventive flow field forces (16) in which thein-filling streams (35) have created the ricochet effect. As can beunderstood by comparison of the direction and velocity of the inventiveflow field forces (16) (as shown in the example of FIG. 4) and theconventional flow field forces (47) (as shown in the example of FIG.3)(arrow heads pointing in the direction of flow and the velocity beinggreater with increasing length of the arrow body) within the respectivepre-combustion chambers (13), the conventional flow field (45) (as shownin the example of FIG. 3) results in greater velocity of thefuel-oxidizer mixture (9) inside the electrode gap (22) moving towardthe internal surface (30) as compared with the inventive flow fieldforces (16) resulting from the ricochet effect (as shown in the exampleof FIG. 4) which has a lesser velocity of the fuel-oxidizer mixture (9)toward and approaching the internal surface (30) of the pre-combustionchamber (13). The comparatively greater velocity of the fuel-oxidizermixture (9) moving toward and approaching internal surface (30) of thepre-combustion chamber (13) (as shown in the example of FIG. 3), such asthe central insulator (17) (including any one or more of the nose (86),lower corner of the nose, the side surface of the nose), can uponignition correspondingly move or locate the flame kernel (44) toward thequenching surfaces of the central insulator (17) (as shown in theexample of FIG. 6) as compared to the inventive flow field forces (16)(as shown in the example of FIG. 4) which has a lesser velocity of thefuel-oxidizer mixture (9) moving toward and approaching the internalsurface (30) of the pre-combustion chamber (13)) which upon ignitioncomparatively locates the flame kernel (44) further away from quenchingsurface of the central insulator (17)(as shown in the example of FIG.7).

Now referring primarily to FIG. 5, as to certain embodiments, thestructure of the pre-combustion chamber (13) and induction ports (31)can achieve sufficient ricochet effect to generate embodiments of theinventive flow field (14) inside of the pre-combustion chamber (13)having sufficient flow field forces (16) to generate a counter flowregion (43) in the electrode gap (22) and even extending about the firstelectrode (18) and the second electrode (21). The counter flow region(43) rather than reducing the velocity of the fuel-oxidizer mixture (9)toward and approaching the internal surface (30) as achieved by theexample of FIG. 4 can in comparison to conventional pre-chamber sparkplugs reverse the direction of flow field forces (16) or create thecounter flow region (43) in the region of the electrode gap (22), andeven about the first electrode (18) and the second electrode (21), whichmoves away from internal surface (30) of the pre-combustion chamber (13)and generally toward the center of the pre-combustion chamber (13). Uponignition of the fuel-oxidizer mixture (9), the flow field forces (16)can be sufficient to move the flame kernel (44) away from quenchingsurface the central insulator (17) (as shown in the example of FIG. 7)and move flame growth (39) toward or into the second recirculation zone(41) having an increased mass of fuel per unit volume or increasedfuel-oxidizer mixture ratio, as compared to conventional pre-chamberspark plugs. Combustion of the fuel-oxidizer mixture (9) in embodimentsof the flow field forces (16) achieving the counter flow region (43) ascompared to combustion of the fuel-oxidizer mixture (9) in conventionalflow fields (45), can occur at substantially increased rates producingflame jets (15) of substantially increased momentum in the maincombustion chamber (3) of an engine (1).

Now referring primarily to FIG. 6 and FIG. 7, which provide side by sidecomparisons of pre-combustion chambers (13) having substantially thesame structure in cross section. FIG. 6 shows conventional flame growth(46) in a pre-combustion chamber (13) in which in-filling streams (35)do not achieve the ricochet effect. FIG. 7 shows inventive flame growth(39) which occurs in embodiments of the inventive flow field (14) havingachieved the ricochet effect. As can be understood, the conventionalflow field (45) (as shown in the example of FIG. 6) within apre-combustion chamber (13) has, upon ignition of the fuel-oxidizermixture (9), sufficient velocity within the region of the electrode gap(22) to move the flame growth (39) toward flame quenching surfaces ofthe central electrode (18), central insulator (17), and the shell (23).As to particular embodiments, the inventive flow field (14) velocitywithin the electrode gap (22) can be between about 1.0 meters per secondand about 100.0 meters per second. As above discussed, increasedinteraction or engulfment of flame kernel (44) and conventional flamegrowth (45) with quenching surfaces can reduce the rate at which thefuel-oxidizer mixture (9) burns in the pre-combustion chamber (13) andcorrespondingly reduces the rate of flame growth and the momentum of theflame jets (15) deployed into the main combustion chamber (3) of engines(1).

Now referring primarily to FIG. 7, which illustrates flame growth (39)in a pre-combustion chamber (13) having a flow field (14) which hasachieved the ricochet effect. The ricochet effect confers severaladvantages over conventional flow fields (45). Firstly, the ricocheteffect can generate flow field forces (16) in the electrode gap (22), asabove described, which can be sufficient to move the flame kernel (44)within the electrode gap (22) away from the internal surface (30) (forexample, the central insulator (17) and shell (23) in the example ofFIG. 7) which can impede, arrest, or slow (collectively “quench”) flamegrowth (39). By reducing interaction or engulfment of the flame kernel(44) with the internal surface (30) of the pre-combustion chamber (13)that quenches flame growth (39) there can be a substantial increase inthe rate of combustion of the fuel-oxidizer mixture (9) inpre-combustion chamber (13). Secondly, movement of the flame kernel (44)in the electrode gap (22) toward the center of the pre-combustionchamber (13) can promote flame growth (39) in the direction of thesecond recirculation zone (41), which as above described, can have anincreased fuel-oxidizer mixture (9) ratio (greater mass of fuel per unitvolume or greater fuel concentration) approaching the center of thepre-combustion chamber (13). The movement of the flame kernel (44)toward greater fuel concentration inside of the pre-combustion chamber(13) can result in substantially increased combustion rates of thefuel-oxidizer mixture (9) inside of the pre-combustion chamber (13) andsubstantially greater momentum of flame jets (15) deployed into the maincombustion chamber (3) of an engine (1).

Now referring to FIG. 8 which shows a cross section 9/10-9/10 whichallows comparison of conventional flow field forces (47) in relation tothe electrode top (48) of the central electrode (18) of a J-gapelectrode (as shown in the example of FIG. 9) and inventive flow fieldforces (49) in relation to the electrode top (48) of a similarlyconfigured central electrode (18) of a J-gap electrode (as shown in theexample of FIG. 10).

Now referring primarily to FIG. 9, the arrows represent the directionsand velocities of conventional flow field forces (47) in the electrodegap (22) of a J-gap electrode in conventional pre-chamber plugs whichhave not achieved the ricochet effect, above described. As shown, theconventional flow field (45) and the corresponding conventional flowfield forces (47) can be substantially disorganized with directions offlow field (14) in several directions which can result in regions withinthe electrode gap (22) which have low flow velocities or even dead zones(50) that have no flow fields (14). This can result in quenching asthere are no flow field forces (16) to move the flame kernel (44) awayfrom the quenching surfaces.

Now referring primarily to FIG. 10, the arrows represent the directionsand velocities of an embodiment of the inventive flow field forces (49)in the electrode gap (22) of a J-gap electrode in embodiments of theinventive pre-combustion chamber unit (13) which have achieved thericochet effect in relation to the electrode gap (22) of a J-gapelectrode, as described in greater detail in the example of FIG. 11. Asshown, the inventive flow field forces (49) and the correspondinginventive flow field (14) can have comparatively greater organization oruniformity with the direction of flow of the fuel-oxidizer mixture (9)in substantially one direction, with greater velocity, and outward fromthe electrode gap (22) and quenching surfaces, or combinations thereof.This can reduce quenching of the flame kernel (44) as there aresufficient flow field forces (16) to quickly move the flame kernel (44)away from the surfaces.

Now referring primarily to FIG. 11, the pre-combustion chamber (13) andinduction ports (31)(34) can be configured in regard to one or moreaspects as above described to achieve ricochet of the in-filling streams(35) from one or more point locations (36) on the internal surface (30)of the pre-combustion chamber (13) which enclose a first electrode (18)and a second electrode (21) in a J-gap configuration. As shown, aparticular embodiment can include an axial induction port (32) whichdirects an in-filling stream (35) toward the second electrode (21) (alsoreferred to as a ground strap). One or more side induction ports (34)(or a first set (51) of side induction ports (34) and a second set (52)of side induction ports (34)) can be configured to direct in-fillingstreams (35) towards corresponding point locations (36) on the opposinginternal surface (30) of the shell (23). The configuration of the one ormore side induction ports (34) (or a first set (51)) can result in anangle of incidence (37) and an angle of deflection (38) in relation tothe one or more point locations (36) to ricochet toward the electrodegap (22). Additionally one or more side induction ports (34) or a secondset (52) can be directed toward the electrode gap (22). The combinedeffect of the ricocheted and directed in-filling streams (35) cangenerate advantageous inventive flow field forces (49) and inventiveflow fields (14) in the pre-combustion chamber (13) enclosing first andsecond electrodes (18)(21) in the J-gap form.

Now referring to FIGS. 12 through 14 and 15 through 17, which showsconventional flame growth (46) (as shown in the examples of FIGS. 12through 14) upon ignition of the fuel-oxidizer mixture (9) of aconventional flow field (45) (as shown in the example of FIG. 9) inrelation to a J-gap electrode (18)(21) as compared to inventive flamegrowth (39) (as shown in the examples of FIGS. 15 through 17) uponignition of the same fuel-oxidizer mixture (9) in the inventive flowfield (14) (as shown in the example of FIG. 10) in relation to asimilarly configured J-gap electrode (18)(21).

Now comparing FIGS. 12 and 15, ignition and initial conventional flamegrowth (46) (as shown in the example of FIG. 12) of the fuel-oxidizermixture (9) in a conventional flow field (45) (as shown in the exampleof FIG. 9) and the ignition and initial inventive flame growth (39) (asshown in the example of FIG. 15) of the fuel-oxidizer mixture (9) in theinventive flow field (14) (as shown in the example of FIG. 10) can besimilar as to certain embodiments, or as to other embodiments theignition spark or the initial flame kernel (44) can be substantiallymoved by the inventive flow field forces (49) as compared to these sameoccurrences as to conventional flow field forces (47).

Now comparing FIGS. 13 and 16, the subsequent development of theinventive flame growth (39) (as shown in the example of FIG. 16)resulting from the combustion of the fuel-oxidizer mixture (9) ofinventive flow field (14) (as shown in the example of 10) as to certainembodiments can occur at an increased rate as compared to theconventional flame growth (46) (as shown in the example of FIG. 13)resulting from the combustion of the fuel-oxidizer mixture (9) of theconventional flow field (45) (as shown by comparing the examples ofFIGS. 13 and 16). Additionally, or in combination with the increasedrate of flame growth (39), the flame growth (39) resulting from thecombustion of the fuel-oxidizer mixture (9) of the inventive flow field(14) can be moved in the direction of the inventive flow field (14) to agreater degree than occurs in the conventional flow field (45) (as shownby comparing the examples of FIGS. 13 and 16).

Now comparing FIGS. 14 and 17, the substantially increased developmentof flame growth (39) (as shown in the example of FIG. 17) resulting fromthe combustion of the fuel-oxidizer mixture (9) of inventive flow field(14) (as shown in the example of FIG. 10) as to certain embodiments canmove outward from the electrode gap (22) in a substantially lesserperiod of time as compared to the conventional flame growth (46) (asshown in the example of FIG. 14) resulting from the combustion of thefuel-oxidizer mixture (9) of the conventional flow field (45) (as shownin the example of FIG. 9). The subsequent rate of flame growth (39)inside the inventive pre-combustion chamber (13) can continue to begreater than in conventional pre-chamber spark plugs.

Now referring primarily to FIGS. 18 through 24, each of which providesan example of a configuration of a first electrode (18) and a secondelectrode (21) at the firing end (53) of a spark plug which can beutilized with embodiments of a pre-combustion chamber unit (2) inaccordance with the invention; however, the invention is not limited tothe electrode configurations shown in FIGS. 18 through 24 which providea sufficient number of examples for the person for ordinary skill tomake and use the invention with a numerous and wide variety of otherelectrode configurations.

Embodiments can include a spark plug including a pre-combustion chamber(13) which, upon installation of said spark plug, has fluidcommunication with the main combustion chamber (3) of an engine (1) viaone or more induction ports (31), and wherein at least two electrodes(18)(21) are disposed within said pre-combustion chamber (3) whichdefine an electrode gap (22) between them, characterized in that atleast one induction port (31) has a configuration so that flow offuel-oxidizer mixture through said at least one induction port (31) intosaid pre-combustion chamber reduces velocity of a flame growth (39) (ora growing flame) formed after ignition through a spark bridging theelectrode gap (22) towards and approaching an internal surface (30) ofsaid pre-combustion chamber.

FIG. 18 depicts the firing end (53) of a dual-bar spark plug electrodegap (as also shown in the examples of FIGS. 2-7). The dual-bar sparkplug electrode structure (54) is typically used in natural gas engines(1) which burn bio-fuels such as landfill gas and digester gas. Thesefuels typically have low energy content and therefore can be susceptibleto quenching during initial flame development. Relatively smallelectrode gap surface area, such as provided by the dual-barconfiguration, can be advantageous for these applications.

FIG. 19 depicts the firing end (53) of a conventional J-gap spark plugelectrode structure (55) (as also shown in the examples of FIGS. 8-17).

FIG. 20 depicts the firing end (53) of an annular spark plug electrodestructure (56). This type of electrode gap (22) is typically used innatural gas engines requiring extended spark plug durability. Theelectrode gap surface area is significantly larger than that of thedual-bar and J-gap spark plug electrode structure (55).

FIG. 21 depicts the firing end (53) of a massive-round spark plugelectrode structure (57). This type of electrode gap (22) is typicallyused in natural gas engines requiring relatively long spark plugdurability. The electrode gap surface area can be larger than that ofthe annular spark plug electrode gap (56).

FIG. 22 depicts the firing end (53) of a three-prong spark plugelectrode structure (58). This type of electrode gap (22) can be used innatural gas engines operating at relatively lower engine powerdensities.

FIG. 23 depicts the firing end of a massive-square spark plug electrodestructure (59). This type of electrode gap (22) is used in natural gasengines operating at relatively higher engine power densities.

FIG. 24 depicts the firing end (53) of a 4-blade spark plug electrodestructure (60). This type of electrode gap (22) can be used in naturalgas engines operating at relatively higher engine power densities.Unlike with the massive type of electrode gaps, the blade type ofelectrode gap can be designed to reduce the aerodynamic obstruction ofthe electrodes.

Now referring to FIGS. 25 through 38 which provide working examples ofparticular embodiments of the invention which achieve the ricocheteffect and exhibit the above-described advantages of achieving thericochet effect; however, it is not intended that the working examplesbe limiting but rather sufficient along with the description and Figuresprovided herein for a person of ordinary skill in the art to make anduse a numerous and wide variety of embodiments of pre-combustion chamberunits (2) in accordance with the invention.

Example 1 Dual Bar-Dual Electrode Gap

Now referring primarily to FIGS. 25 through 29, which provides a workingexample of a particular embodiment of the inventive pre-chamber unit (2)having a first electrode (18) in the form a central electrode (63) and asecond electrode (21) in the form of a grounded dual bar electrode (54)(as shown in the example of FIG. 18) in the form of a first bar (61) anda second bar (62) disposed a distance apart with the first electrode(18) in the form of a central electrode (63) having a location betweenthe first bar (61) and the second bar (62) to provide a dual electrodegap (as shown in the example of FIG. 18 and the examples of FIGS. 2through 7). A central insulator (17) surrounds the central electrode(63). A metallic shell (23) encases the central electrode (63) andextends outwardly to provide a pre-combustion chamber (13) having agenerally cylindrical shell external surface (24) and generallycylindrical shell pre-combustion chamber internal surface (30)surrounding the central insulator (17) and the first electrode (18) andthe second electrode (21). The pre-combustion chamber (13) having agenerally flat pre-combustion chamber top (64) (as shown in the examplesof FIGS. 25 through 29). A pre-combustion chamber inner diameter (65)can be provided in the range of about 9 mm and about 13 mm (as shown inthe example of FIG. 29). The pre-combustion chamber (13) can have aninsertion depth (66)(that portion of the external surface (28) extendinginto the main combustion chamber (3)) of between about 6 mm and about 8mm (as shown in the example of FIG. 29).

The relationship of the internal surface (30) of the pre-combustionchamber (13) can enclose a total volume (67) of between about 800 mm³and about 1000 mm³ (as shown in the example of FIG. 25). Theconfiguration of the pre-combustion chamber (13) forward of theelectrode gap (22) can enclose a first pre-combustion chamber volume(68) of between about 350 mm³ and about 450 mm³ (as shown in the exampleof FIG. 26). The first pre-combustion chamber volume (68) can beadjusted, for example, by increasing or decreasing the pre-combustionchamber inner diameter (65) of the cylindrical internal surface (30)defining the first pre-combustion chamber volume (68). The configurationof the pre-combustion chamber (13) rearward of the electrode gap (22)can enclose a second pre-combustion chamber volume (69) of between about450 mm³ and about 550 mm³ (as shown in the example of FIG. 27). Thesecond pre-combustion chamber volume (69) can be adjusted, for example,by increasing or decreasing the pre-combustion chamber inner diameter(65) of cylindrical internal surface (30) defining the secondpre-combustion chamber volume (69). The example of FIGS. 25-29, having afirst pre-chamber volume (68) defined by a greater diameter of theinternal surface (30) of pre-combustion chamber (13) and having a secondpre-chamber volume (69) defined by a lesser diameter of the internalsurface (30) of the pre-combustion chamber (13), respectively. Theheight (70) of the first pre-combustion chamber volume (68) can be inthe range of about 3 mm to about 5 mm (as shown in the example of FIG.29).

The pre-combustion chamber (13) whether formed by extension of the shell(23) or by coupling of a pre-combustion chamber element (26) to the baseof the shell (23), or otherwise, can have an axial induction port (32)substantially axially aligned with the central longitudinal axis (33) ofthe pre-chamber unit (2) (as shown in the example of FIG. 29). The axialinduction port (32) can have a length (71) along the longitudinal axis(33) between the external surface (28) and the internal surface (30) ofthe pre-combustion chamber (13) in the range of about 2 mm to about 4 mm(being the thickness of the pre-combustion chamber wall (27)) (as shownin the example of FIG. 29). The axial induction port (32) can have adiameter (72) of between about 1 millimeter and about 2 millimeters (asshown in the example of FIG. 29).

Now referring primarily to FIG. 28, each of the side induction ports(34) can have a diameter (72) in the range of about 1 mm and about 2millimeters (“mm”) (as shown in the example of FIG. 28). Each sideinduction port (34) can have an external port aperture (73) locatedradially outward from the axial induction port (32) at a first radius(75) of between about 5 mm and about 7 mm (as shown in the example ofFIG. 28). Each of the side induction ports (34) can communicate betweenthe external surface (28) and the internal surface (30) of thepre-combustion chamber wall (27) inwardly at a side induction port angle(78) in the range of about 20 degrees and about 30 degrees (as shown inthe example of FIG. 28) to correspondingly locate an internal portaperture (74) on the internal surface (30) of the pre-combustion chamber(13) (as shown in the example of FIG. 28).

Example 2 J-Gap Electrode

Now referring primarily to FIGS. 30 through 38, which provides a workingexample of particular embodiment of the inventive pre-chamber unit (2)having a first electrode (18) in the form a central electrode (63) and asecond electrode (21) in the form of a grounded J-electrode (also shownin the example of FIGS. 19 and 10-11 and 15-17) disposed a distanceaxially above the central electrode (63) to provide an electrode gap(22) (as shown in the example of FIG. 30). A central insulator (17)surrounds the central electrode (63). A metallic shell (23) encases thecentral electrode (63) and extends outwardly to provide a pre-combustionchamber (13) having a generally cylindrical shell external surface (24)and generally cylindrical internal surface (30) surrounding the centralinsulator (17) and the first electrode (18) and the second electrode(21). The substantially closed end of the cylindrical pre-combustionchamber (13) having a flat pre-combustion chamber top (64) (as shown inthe examples of 30-38). The pre-combustion chamber inner diameter (65)can be provided in the range of about 9 mm and about 13 mm (as shown inthe example of FIG. 34). The pre-combustion chamber (13) can have aninsertion depth (66) (that portion extending into the main combustionchamber (3)) of between about 3 mm and about 5 mm (as shown in theexample of FIG. 34).

The relationship of the internal surface (30) of the pre-combustionchamber (13) can enclose a total volume (67) of between about 800 mm³and about 1000 mm³ (as shown in the example of FIG. 30). Theconfiguration of the pre-combustion chamber (13) forward of theelectrode gap (22) can enclose a first pre-combustion chamber volume(68) of between about 550 mm³ and about 650 mm³ (as shown in the exampleof FIG. 31). The first pre-combustion chamber volume (68) can beadjusted, for example, by increasing or decreasing the pre-combustionchamber inner diameter (65) of the cylindrical internal surface definingthe first pre-combustion chamber volume (68). The configuration of thepre-combustion chamber (13) rearward of the electrode gap (22) canenclose a second pre-combustion chamber volume (69) of between about 250mm³ and about 350 mm³ (as shown in the example of FIG. 32). The secondpre-combustion chamber volume (69) can be adjusted, for example, byincreasing or decreasing the pre-combustion chamber inner diameter (65)of cylindrical internal surface defining the second pre-combustionchamber volume (69). The example of FIGS. 30 through 38, having a firstpre-chamber volume (68) defined by a greater diameter of the internalsurface of pre-combustion chamber (13) and having a second pre-chambervolume (69) defined by a lesser diameter of the internal surface (30) ofthe pre-combustion chamber (13), respectively. The height (70) of thefirst pre-combustion chamber volume (68) measured from about theelectrode top (48) of the central electrode (63) to the inner surface ofthe pre-combustion chamber top (64) can be in the range of about 6 mm toabout 8 mm (as shown in the example of FIG. 34).

The pre-combustion chamber (13) whether formed by extension of the shell(23) or by coupling of a pre-combustion chamber element (26) to the baseof the shell (23), or otherwise, can have an axial induction port (32)substantially axially aligned with the central longitudinal axis (33) ofthe pre-chamber unit (2)(as shown in the example of FIG. 34). The axialinduction port (32) can have a length (71) along the longitudinal axis(33) between the external surface (28) and the internal surface (30) ofthe pre-combustion chamber top (64) in the range of about 2 mm to about4 mm (being the thickness of the pre-combustion chamber wall (27))(asshown in the example FIG. 34). The axial induction port (32) can have adiameter (72) of between about 1 millimeter and about 2 millimeters(“mm”) (as shown in the example of FIG. 33).

As shown in FIG. 33, the pre-combustion chamber (13) can include betweensix and eight side induction ports (34) located radially outward of andgenerally equally radially spaced about the axial induction port (32).The side induction ports (34) can comprise a first set (51) of betweenthree and four side induction ports (34) and second set (52) of betweenthree and four side induction ports (34), each of the first and secondset (51)(52) can have a different structure.

Now referring primarily to FIGS. 35 and 36, each of the first set (51)of side induction ports (34) can have a diameter (72) in the range ofabout 1 mm and about 2 millimeters (“mm”) (as shown in the example ofFIG. 33). Each of the first set (51) of side induction ports (34) canhave an external port aperture (73) located radially outward from thecentral longitudinal axis (33) at a first radius (75) of between about 6mm and about 8 mm (as shown in the example of FIG. 36). Each of thefirst set (51) of side induction ports (34) can have a swirl offset (77)of between 3 mm to 4 mm which defines the perpendicular distance betweenthe side induction port central axis (76) and the central longitudinalaxis (33) of the inventive pre-chamber unit (as shown in the example ofFIG. 35). Each of the first set (51) of side induction ports (34) cancommunicate between the external surface (28) and the internal surface(30) of the pre-combustion chamber wall (27) inwardly at a sideinduction port angle (78) in the range of about 25 degrees to about 35degrees (as shown in the example of FIG. 36). The external port aperture(73) of each of the first set (51) of side induction ports (34) could bespaced equally and with a single side induction port (34) being locatedat a first index angle (79) of about 30 degrees to about 40 degrees fromthe ground strap electrode (21) reference location (80) (as shown in theexample of FIG. 35).

Now referring primarily to FIGS. 37 and 38, each of the second set (52)of side induction ports (34) can have a diameter (72) in the range ofabout 1 mm and about 2 millimeters (“mm”) (as shown in the example ofFIG. 33). Each of the second set (52) of side induction ports (34) canhave an external port aperture (73) located radially outward from thecentral longitudinal axis (33) at a second radius (81) of between about7 mm and about 9 mm (as shown in the example of FIG. 38). Each of thesecond set (52) of side induction ports (34) can have a second swirloffset (83) of between 1 mm to 2 mm which defines the perpendiculardistance between the side induction port central axis (82) and thecentral longitudinal axis (33) of the inventive pre-chamber unit (asshown in the example of FIG. 37). Each of the second set (52) of sideinduction ports (34) can communicate between the external surface (28)and the internal surface (30) of the pre-combustion chamber wall (27)inwardly at a second side induction port angle (84) in the range ofabout 50 degrees to about 60 degrees (as shown in the example of FIG.38). The external port aperture (73) of each of the second set (52) ofside induction ports (34) could be spaced equally and with a single sideinduction port (34) being located at a second index angle (85) of about80 degrees to about 100 degrees from the ground strap electrode (21)reference location (80) (as shown in the example of FIG. 37).

In certain embodiments, the design of the prechamber may be matched tothe design of the spark plug electrode gap. In certain embodiments, thematching may take place by calculating the flow fields at the gap andwithin the prechamber and the resulting effects on flame quenching, rateof combustion and the electrodes wear rate. The term “matching” may meanthat the geometry of the prechamber, in terms of all its parameters suchas volume, aspect ratio, holes' diameter, penetration angle, rotationaloffset and so on, may be arranged with the use of Computational FluidDynamics (CFD) to create the most advantageous flow field and lambdadistribution at the gap and within the prechamber. In certainembodiments, the term “most advantageous” may include one or more of thefollowing characteristics:

-   -   The flow velocity in the gap may be substantially uniform in        magnitude and direction.    -   The magnitude of the flow in the gap may be less than about 50        m/s.    -   The flow from the gap may be directed away from quenching        surfaces and towards the prechamber exit orifices (holes).    -   The flow in the prechamber may have an average turbulent kinetic        energy greater than about 1 m²/s².    -   The lambda distribution in the gap may be substantially uniform.    -   The magnitude of lambda in the gap may be richer than about 2.5.    -   The lambda distribution in the prechamber may be richer in the        region comprised between the gap and the exit orifices and        leaner in the region comprised between the gap and the bottom of        the prechamber.    -   The magnitude of the average lambda in the prechamber may be        richer than about 2.5.

In certain embodiments, FIG. 39 shows the uniform flow velocity andmagnitude in the gap 3903 of a permanent passive prechamber 3901 withremovable spark plug 3902. It also shows that the flow from the gap maybe directed away from quenching surfaces and towards the prechamber exitorifices/holes 3904.

In certain embodiments, FIG. 40 shows uniform Lambda distribution 4002in the gap of a permanent passive prechamber with a removable sparkplug. It also shows Lambda stratification in the prechamber that isricher 4003 in the region comprised between the gap and the exitorifices and leaner 4001 in the region comprised between the gap and thebottom of the prechamber.

In certain embodiments, the spark plug and prechamber may be matched tothe quality of the fuel. In certain embodiments, the aspect of matchingthe combination of spark plug design and forward flow prechamber designto the fuel quality defined as energy content (LHV) and propensity toknock (MN) is shown in FIG. 41. In certain embodiments, the matching maytake place by calculating the flow fields at the gap and within theprechamber and the resulting effects on flame quenching, rate ofcombustion and electrodes wear rate. In certain embodiments, FIG. 41shows a correlation between the type of fuel, the Low Heating Value(LHV) and the fuel Methane Number (MN).

In certain embodiments, the term “matching” may mean that the geometryof the prechamber, in terms of all its parameters such as volume, aspectratio, holes' diameter, penetration angle, rotational offset and so on,is arranged with the use of CFD to create the most advantageous flowfield and lambda distribution at the gap and within the prechamber. Theterm “most advantageous” may include one or more of the followingcharacteristics:

-   -   The flow velocity in the gap may be uniform in magnitude and        direction.    -   The magnitude of the flow in the gap may be less than about 50        m/s.    -   The flow from the gap may be directed away from quenching        surfaces and towards the prechamber exit orifices (holes).    -   The flow in the prechamber may have an average turbulent kinetic        energy greater than about 1 m²/s².    -   The lambda distribution in the gap may be uniform.    -   The magnitude of lambda in the gap may be richer than about 2.5.    -   The lambda distribution in the prechamber may be richer in the        region between the gap and the exit orifices and leaner in the        region between the gap and the bottom of the prechamber.    -   The magnitude of the average lambda in the prechamber may be        richer than about 2.5.    -   For fuels with energy content greater than about 800 BTU/ft³,        the total volume of the prechamber may be in the range of about        1000-6000 mm³ as shown in FIG. 42.    -   For fuels with energy content lower than about 800 BTU/ft³, the        total volume of the prechamber should be greater than about 1000        mm³ as shown in FIG. 43.    -   For fuels with Methane Number (MN) greater than about 60, the        total volume of the prechamber may be in the range of about        1000-6000 mm³ as shown in FIG. 44.

In certain embodiments, FIG. 42 shows a permanent passive prechamber4201 with removable spark plug 4202 for natural gas fueled engines withmedium pre-chamber volume 4203 as compared to general configurations forthe other types of fuels.

In certain embodiments, FIG. 43 shows a permanent passive prechamber4301 with removable spark plug 4302 for low BTU fueled engines as withlargest pre-chamber volume 4303 compared to general configurations forthe other types of fuels.

In certain embodiments, FIG. 44 shows a permanent passive prechamber4401 with removable spark plug 4402 for greater than about 60 MN fueledengines with a medium prechamber volume 4403 as compared to generalconfigurations for the other types of fuels.

In certain embodiments, FIG. 45 shows a permanent passive prechamber4501 with removable spark plug 4502 for low MN fueled engines with asmallest pre-chamber volume 4503 as compared to general configurationsfor the other types of fuels.

In certain embodiments, FIG. 46 shows uniform flow velocity andmagnitude in the gap of a forward flow prechamber spark plug 4602. Italso shows that the flow from the gap 4601 may be directed away fromquenching surfaces and towards the prechamber exit orifices (holes).

In certain embodiments, FIG. 47 shows uniform Lambda distribution in thegap 4702 of a forward flow prechamber spark plug. It also shows Lambdastratification in the prechamber that is richer 4703 in the regionbetween the gap and the exit orifices and leaner 4701 in the regioncomprised between the gap and the bottom of the prechamber.

In certain embodiments, the thermal dissipation characteristics of aselected combination of spark plug design and forward flow prechamberdesign may be optimized. The optimization may be determined bycalculating the temperatures of the various elements defining thecombination and the resulting effects on flame quenching, rate ofcombustion and the electrodes wear rate. In certain embodiments, theterm “matching” may mean that the geometry of the prechamber, in termsof all its parameters such as volume, aspect ratio, holes' diameter,penetration angle, rotational offset and so on, may be arranged with thecombined use of CFD and thermal finite element analysis (FEA) to createthe most advantageous flow field and lambda distribution at the gap andwithin the prechamber while achieving optimum surface temperatures ofthe various elements constituting the spark plug and the prechamber. Theterm “most advantageous” may include one or more of the followingcharacteristics:

-   -   The flow velocity in the gap may be uniform in magnitude and        direction.    -   The magnitude of the flow in the gap may be less than about 50        m/s.    -   The flow from the gap may be directed away from quenching        surfaces and towards the prechamber exit orifices (holes).    -   The flow in the prechamber may have an average turbulent kinetic        energy greater than about 1 m²/s².    -   The lambda distribution in the gap may be uniform.    -   The magnitude of lambda in the gap may be richer than about 2.5.    -   The lambda distribution in the prechamber may be richer in the        region comprised between the gap and the exit orifices and        leaner in the region comprised between the gap and the bottom of        the prechamber.    -   The magnitude of the average lambda in the prechamber may be        richer than about 2.5.    -   The inner walls of the prechamber may not exceed 900 C.    -   The ground electrode temperature may not exceed 900 C.    -   The center electrode temperature may not exceed 900 C.    -   The spark plug core nose temperature may not exceed 800 C.    -   The spark plug hot lock temperature may not exceed 300 C.    -   The spark plug roll over temperature may not exceed 300 C.    -   The prechamber end-cap temperature may not exceed 1000 C.

In certain embodiments, FIG. 48 shows a temperature distribution in themajor elements of a forward flow prechamber spark plug. Varioustemperatures may be achieved depending on the material used and type ofconstruction. In certain embodiments, FIG. 48 shows ground electrodetemperature 4801; center electrode temperature 4802; prechamberinner-wall temperature 4803; and prechamber outer-wall temperature 4804.

In certain embodiments, FIG. 49 shows a temperature distribution in themajor elements of a removable spark plug and permanent prechamber.Various temperatures can be achieved depending on the material used andtype of construction. In certain embodiments, FIG. 49 shows groundelectrode temperature 4901; center electrode temperature 4902;prechamber inner-wall temperature 4903; and prechamber outer-walltemperature 4904.

In certain embodiments, all the prechamber geometrical parameters may bearranged with the combined use of CFD and thermal FEA to create the mostadvantageous flow field and lambda distribution at the gap and withinthe prechamber, while achieving optimum surface temperatures. Below aresome CFD and FEA examples.

In certain embodiments, FIG. 50 shows an active scavenge prechamberspark plug with a scavenging port 5002 located remotely from the radialgap 5001. In certain embodiments, FIG. 51 shows an active scavengeprechamber spark plug with a scavenging port 5102 located adjacent tothe radial gap 5101. In certain embodiments, FIG. 52 shows a flowvelocity pattern 5202 and uniform magnitude in a single radial gap 5201of an active scavenge prechamber spark plug. It also shows that theuniform flow from the gap 5201 is directed away from quenching surfacesand towards the prechamber exit orifices/holes 5203. In certainembodiments, FIG. 53 shows uniform flow velocity and magnitude 5301 in asingle radial gap of an active scavenge prechamber spark plug. Incertain embodiments, FIG. 54 shows Lambda stratification in a prechamberthat is richer in the region 5402 comprised between the gap and the exitorifices and leaner in the region 5401 between the gap and the bottom ofthe prechamber. In certain embodiments, FIG. 55 shows the uniform Lambdadistribution 5501 in the single radial gap. In certain embodiments, FIG.56 shows a temperature distribution in the major elements of an activescavenge prechamber spark plug with single radial gap. Varioustemperatures can be achieved depending on the material used and type ofconstruction. FIG. 56 shows pre-chamber spark plug 5603; centerelectrode 5602; ground electrode 5601; and pre-chamber volume 5604.

In certain embodiments, a large electrode surface may be defined aslarger than about 2 mm². For electrode surfaces greater than about 2mm², it may be very difficult to achieve uniform flow velocities andlambda distributions. For example, an electrode surface of about 9 mm²may be used. With such a large electrode surface, the spark plug lifemay be greatly enhanced. This advantage may be achieved withoutsubstantial penalty to the ignitability performance, which may beassured by the uniform flow velocities and lambda distributions asdescribed above. In order to achieve these conditions, the geometricalparameters of the prechamber may be arranged with the use of CFD andthermal FEA to create the most advantageous flow field and lambdadistribution at the gap and within the prechamber while achievingoptimum surface temperatures of the various elements constituting thespark plug and the prechamber. The ranges and criteria pertaining toflow fields, lambda distributions and temperatures may be the same asprovided above. In certain embodiments, FIG. 57 shows a removable sparkplug 5701 with radial gap 5703, screwed into a pre-chamber 5702.

As can be easily understood from the foregoing, the basic concepts ofthe present invention may be embodied in a variety of ways. Theinvention involves numerous and varied embodiments of an inventivepassive chamber spark plug including devices and methods for using suchdevices including the best mode.

As such, the particular embodiments or elements of the inventiondisclosed by the description or shown in the figures or tablesaccompanying this application are not intended to be limiting, butrather exemplary of the numerous and varied embodiments genericallyencompassed by the invention or equivalents encompassed with respect toany particular element thereof. In addition, the specific description ofa single embodiment or element of the invention may not explicitlydescribe all embodiments or elements possible; many alternatives areimplicitly disclosed by the description and figures.

It should be understood that each element of an apparatus or each stepof a method may be described by an apparatus term or method term. Suchterms can be substituted where desired to make explicit the implicitlybroad coverage to which this invention is entitled. As but one example,it should be understood that all steps of a method may be disclosed asan action, a means for taking that action, or as an element which causesthat action. Similarly, each element of an apparatus may be disclosed asthe physical element or the action which that physical elementfacilitates. As but one example, the disclosure of a “spark” should beunderstood to encompass disclosure of the act of “sparking”—whetherexplicitly discussed or not—and, conversely, were there effectivelydisclosure of the act of “sparking”, such a disclosure should beunderstood to encompass disclosure of a “spark” and even a “means forsparking.” Such alternative terms for each element or step are to beunderstood to be explicitly included in the description.

In addition, as to each term used it should be understood that unlessits utilization in this application is inconsistent with suchinterpretation, common dictionary definitions should be understood toincluded in the description for each term as contained in the RandomHouse Webster's Unabridged Dictionary, second edition, each definitionhereby incorporated by reference.

All numeric values herein are assumed to be modified by the term“about”, whether or not explicitly indicated. For the purposes of thepresent invention, ranges may be expressed as from “about” oneparticular value to “about” another particular value. When such a rangeis expressed, another embodiment includes from the one particular valueto the other particular value. The recitation of numerical ranges byendpoints includes all the numeric values subsumed within that range. Anumerical range of one to five includes for example the numeric values1, 1.5, 2, 2.75, 3, 3.80, 4, 5, and so forth. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint. When a value is expressed as an approximation by use of theantecedent “about,” it will be understood that the particular valueforms another embodiment. The term “about” generally refers to a rangeof numeric values that one of skill in the art would consider equivalentto the recited numeric value or having the same function or result.Similarly, the antecedent “substantially” means largely, but not wholly,the same form, manner or degree and the particular element will have arange of configurations as a person of ordinary skill in the art wouldconsider as having the same function or result. When a particularelement is expressed as an approximation by use of the antecedent“substantially,” it will be understood that the particular element formsanother embodiment.

Moreover, for the purposes of the present invention, the term “a” or“an” entity refers to one or more of that entity unless otherwiselimited. As such, the terms “a” or “an”, “one or more” and “at leastone” can be used interchangeably herein.

Thus, the applicant(s) should be understood to claim at least: i) eachof the pre-chamber units or pre-chamber spark plugs herein disclosed anddescribed, ii) the related methods disclosed and described, iii)similar, equivalent, and even implicit variations of each of thesedevices and methods, iv) those alternative embodiments which accomplisheach of the functions shown, disclosed, or described, v) thosealternative designs and methods which accomplish each of the functionsshown as are implicit to accomplish that which is disclosed anddescribed, vi) each feature, component, and step shown as separate andindependent inventions, vii) the applications enhanced by the varioussystems or components disclosed, viii) the resulting products producedby such systems or components, ix) methods and apparatuses substantiallyas described hereinbefore and with reference to any of the accompanyingexamples, x) the various combinations and permutations of each of theprevious elements disclosed.

The background section of this patent application provides a statementof the field of endeavor to which the invention pertains. This sectionmay also incorporate or contain paraphrasing of certain United Statespatents, patent applications, publications, or subject matter of theclaimed invention useful in relating information, problems, or concernsabout the state of technology to which the invention is drawn toward. Itis not intended that any United States patent, patent application,publication, statement or other information cited or incorporated hereinbe interpreted, construed or deemed to be admitted as prior art withrespect to the invention.

The claims set forth in this specification, if any, are herebyincorporated by reference as part of this description of the invention,and the applicant expressly reserves the right to use all of or aportion of such incorporated content of such claims as additionaldescription to support any of or all of the claims or any element orcomponent thereof, and the applicant further expressly reserves theright to move any portion of or all of the incorporated content of suchclaims or any element or component thereof from the description into theclaims or vice-versa as necessary to define the matter for whichprotection is sought by this application or by any subsequentapplication or continuation, division, or continuation-in-partapplication thereof, or to obtain any benefit of, reduction in feespursuant to, or to comply with the patent laws, rules, or regulations ofany country or treaty, and such content incorporated by reference shallsurvive during the entire pendency of this application including anysubsequent continuation, division, or continuation-in-part applicationthereof or any reissue or extension thereon.

The claims set forth in this specification, if any, are further intendedto describe the metes and bounds of a limited number of the preferredembodiments of the invention and are not to be construed as the broadestembodiment of the invention or a complete listing of embodiments of theinvention that may be claimed. The applicant does not waive any right todevelop further claims based upon the description set forth above as apart of any continuation, division, or continuation-in-part, or similarapplication.

We claim:
 1. A method of distributing a fuel-oxidizer mixture in apre-combustion chamber, comprising: providing a pre-combustion chambercomprising: a primary electrode and one or more ground electrodesdisposed within the pre-combustion chamber, the primary electrode andthe ground electrode disposed a distance apart to provide one or moreelectrode gaps; at least one induction port which communicates betweenan external surface and an internal surface of said pre-combustionchamber; and directing a fuel-oxidizer mixture into the pre-combustionchamber via the at least one induction port to reduce interaction of aflame kernel with an internal surface of said pre-combustion chamber. 2.The method of claim 1, wherein the ground electrodes comprise a singleground electrode disposed a distance apart from the primary electrode toform a single electrode gap.
 3. The method of claim 2, wherein thesingle ground electrode has a surface area greater than about 1 mm². 4.The method of claim 2, wherein the pre-combustion chamber is configuredto generate a flow velocity in the single electrode gap of the sparkplug that is less than about 100 m/s when a fuel air mixture is ignitedin the pre-combustion chamber.
 5. The method of claim 1, wherein thepre-combustion chamber is configured to generate an average turbulentkinetic energy greater than 1 m²/s² when a fuel air mixture is ignitedin the pre-combustion chamber.
 6. The method of claim 2, wherein thepre-combustion chamber is configured to generate a substantially uniformlambda distribution in the single electrode gap of the spark plug when afuel air mixture is ignited in the pre-combustion chamber.
 7. The methodof claim 2, wherein the pre-combustion chamber is configured to generatea lambda fuel air mixture richer than about 2.5 in the single electrodegap of the spark plug when a fuel air mixture is ignited in thepre-combustion chamber.
 8. The method of claim 1, wherein thepre-combustion chamber is configured to generate an average lambda valuericher than about 2.5 in the pre-combustion chamber when a fuel airmixture is ignited in the pre-combustion chamber.
 9. The method of claim1, wherein the volume of the pre-combustion chamber is between about1000 mm³ and about 6000 mm³ for use with fuels with energy contentgreater than about 800 BTU/ft³.
 10. The method of claim 1, wherein thepre-combustion chamber has a total volume greater than about 1000 mm³for use with fuels with energy content less than about 800 BTU/ft³. 11.The method of claim 1, wherein the pre-combustion chamber has a totalvolume less than about 6000 mm³ for use with fuels with Methane Numberlower than about
 60. 12. The method of claim 1, wherein thepre-combustion chamber has a total volume between about 1000 mm³ andabout 6000 mm³ for use with fuels with Methane Number greater than about60.
 13. The method of distributing a fuel-oxidizer mixture in apre-combustion chamber of claim 1, further comprising directing afuel-oxidizer mixture into the pre-combustion chamber via the at leastone induction port to increase a fuel-oxidizer mixture ratio within saidpre-combustion chamber toward a center of said pre-combustion chamber.14. The method of distributing a fuel-oxidizer mixture in apre-combustion chamber of claim 1, further comprising directing afuel-oxidizer mixture into the pre-combustion chamber via the at leastone induction port to reduce quenching of said flame kernel on saidinternal surface of said pre-combustion chamber.
 15. The method ofdistributing a fuel-oxidizer mixture in a pre-combustion chamber ofclaim 1, further comprising: surrounding a first of said one or moreelectrodes with a central insulator, said central insulator encased in ashell extending outwardly about said one or more electrodes; andgenerating flow field forces within said electrode gap sufficient toreduce interaction of said flame kernel with said central insulator. 16.The method of distributing a fuel-oxidizer mixture in a pre-combustionchamber of claim 1, further comprising generating a flow field velocitywithin said electrode gap of between about 1.0 meter per second andabout 100.0 meters per second.
 17. A method of distributing afuel-oxidizer mixture in a pre-combustion chamber, comprising providinga pre-combustion chamber comprising: a primary electrode and a groundelectrode disposed within the pre-combustion chamber, the primaryelectrode and the ground electrode disposed a distance radially apart toprovide a single electrode gap; at least one induction port whichcommunicates between an external surface and an internal surface of saidpre-combustion chamber; the at least one induction port configured toaim at least one infilling stream of said fuel-oxidizer mixture at saidinternal surface of said pre-combustion chamber; and introducing atleast one infilling stream of fuel-oxidizer mixture into thepre-combustion chamber via the at least one induction port.
 18. Themethod of claim 17, wherein the ground electrode comprises an electrodesurface area greater than about 1 mm².
 19. The method of claim 17,wherein the pre-combustion chamber is configured to generate a flowvelocity in the single electrode gap of the spark plug that is less thanabout 100 m/s when a fuel air mixture is ignited in the pre-combustionchamber.
 20. The method of claim 17, wherein the pre-combustion chamberis configured to generate an average turbulent kinetic energy greaterthan 1 m²/s² when a fuel air mixture is ignited in the pre-combustionchamber.
 21. The method of claim 17, wherein the pre-combustion chamberis configured to generate a substantially uniform lambda distribution inthe single electrode gap of the spark plug when a fuel air mixture isignited in the pre-combustion chamber.
 22. The method of claim 17,wherein the pre-combustion chamber is configured to generate a lambdafuel air mixture richer than about 2.5 in the single electrode gap ofthe spark plug when a fuel air mixture is ignited in the pre-combustionchamber.
 23. The method of claim 17, wherein the pre-combustion chamberis configured to generate a lambda fuel air mixture richer than in asecond region between the single electrode gap of the spark plug and abottom surface of the pre-combustion chamber when a fuel air mixture isignited in the pre-combustion chamber.
 24. The method of claim 17,wherein the pre-combustion chamber is configured to generate an averagelambda value richer than about 2.5 in the pre-combustion chamber when afuel air mixture is ignited in the pre-combustion chamber.
 25. Themethod of claim 17, wherein the volume of the pre-combustion chamber isbetween about 1000 mm³ and about 6000 mm³ for use with fuels with energycontent greater than about 800 BTU/ft³.
 26. The method of claim 17,wherein the pre-combustion chamber has a total volume greater than about1000 mm³ for use with fuels with energy content less than about 800BTU/ft³.
 27. The method of claim 17, wherein the pre-combustion chamberhas a total volume less than about 6000 mm³ for use with fuels withMethane Number lower than about
 60. 28. The method of claim 17, whereinthe pre-combustion chamber has a total volume between about 1000 mm³ andabout 6000 mm³ for use with fuels with Methane Number greater than about60.
 29. The method of distributing a fuel-oxidizer mixture in apre-combustion chamber of claim 17, further comprising configuring saidat least one induction port to aim at least one infilling stream of saidfuel-oxidizer mixture at least one point location on said internalsurface of said pre-combustion chamber selected from the groupconsisting of: a core nose of a central insulator, an upper corner ofsaid core nose of said central insulator, one or more electrodes, andsaid shell.
 30. The method of distributing a fuel-oxidizer mixture in apre-combustion chamber of claim 17, further comprising ricocheting saidat least one infilling stream from said internal surface of saidpre-combustion chamber to achieve reduced interaction of said flamekernel with said internal surface of said pre-combustion chamber.
 31. Apre-chamber unit, comprising: a primary electrode and a ground electrodedisposed a distance radially apart to provide a single electrode gap; apre-combustion chamber which at least partially encloses said firstelectrode and said second electrode; and at least one induction portwhich communicates between an external surface and an internal surfaceof said pre-combustion chamber, said at least one induction portconfigured to direct a fuel-oxidizer mixture into the pre-combustionchamber to generate flow field forces within said pre-combustion chamberwhich upon ignition of a fuel-oxidizer mixture reduce the interaction ofa flame kernel with said internal surface of said pre-combustionchamber.
 32. The pre-chamber unit of claim 31, wherein the groundelectrode comprise an electrode surface area greater than about 1 mm².33. The pre-chamber unit of claim 31, wherein the pre-combustion chamberis configured to generate a flow velocity in the single electrode gap ofthe spark plug that is less than about 100 m/s when a fuel air mixtureis ignited in the pre-combustion chamber.
 34. The pre-chamber unit ofclaim 31, wherein the pre-combustion chamber is configured to generatean average turbulent kinetic energy greater than 1 m²/s² when a fuel airmixture is ignited in the pre-combustion chamber.
 35. The pre-chamberunit of claim 31, wherein the pre-combustion chamber is configured togenerate a substantially uniform lambda distribution in the singleelectrode gap of the spark plug when a fuel air mixture is ignited inthe pre-combustion chamber.
 36. The pre-chamber unit of claim 31,wherein the pre-combustion chamber is configured to generate a lambdafuel air mixture richer than about 2.5 in the single electrode gap ofthe spark plug when a fuel air mixture is ignited in the pre-combustionchamber.
 37. The pre-chamber unit of claim 31, wherein thepre-combustion chamber is configured to generate a lambda fuel airmixture richer than in a second region between the single electrode gapof the spark plug and a bottom surface of the pre-combustion chamberwhen a fuel air mixture is ignited in the pre-combustion chamber. 38.The pre-chamber unit of claim 31, wherein the pre-combustion chamber isconfigured to generate an average lambda value richer than about 2.5 inthe pre-combustion chamber when a fuel air mixture is ignited in thepre-combustion chamber.
 39. The pre-chamber unit of claim 31, whereinthe volume of the pre-combustion chamber is between about 1000 mm³ andabout 6000 mm³ for use with fuels with energy content greater than about800 BTU/ft³.
 40. The pre-chamber unit of claim 31, wherein thepre-combustion chamber has a total volume greater than about 1000 mm³for use with fuels with energy content less than about 800 BTU/ft³. 41.The pre-chamber unit of claim 31, wherein the pre-combustion chamber hasa total volume less than about 6000 mm³ for use with fuels with MethaneNumber lower than about
 60. 42. The pre-chamber unit of claim 31,wherein the pre-combustion chamber has a total volume between about 1000mm³ and about 6000 mm³ for use with fuels with Methane Number greaterthan about
 60. 43. The pre-chamber unit of claim 31, wherein a flowfield velocity within said electrode gap has a range of between about1.0 m/s and about 100.0 m/s.
 44. The pre-chamber unit of claim 31,wherein said at least one induction port is configured to aim at leastone infilling stream toward a selected one or more of: a nose of acentral insulator, an upper corner of a nose of a central insulator, alower corner of a nose of a central insulator, a side surface of a noseof a central insulator, and a shell.
 45. The pre-chamber unit of claim31, wherein said internal surface comprises a central insulator fromwhich said at least one infilling stream is configured to ricochet togenerate said flow field forces to increase said fuel-oxidizer mixtureratio in said electrode gap.
 46. The pre-chamber unit of claim 31,wherein said pre-combustion chamber encloses a total volume of betweenabout 800 millimeters³ and about 1000 millimeters³.
 47. The pre-chamberunit of claim 31, wherein the at least one induction port is configuredto develop flow field forces which increase mixing of an amount ofresidual gases within said pre-combustion chamber with said in-fillingstreams to reduce temperature of said internal surface of saidpre-chamber or said amount of residual gases.